
rkss QJ5C 

Book 5 5*^ 

If 4- 



SMITHSONIAN DEPOSIT. 



n 

SITJ 



i 



i 



FIRST PRINCIPLES 



CHEMISTRY 



FOR THE USE OF 



COLLEGES AND SCHOOLS. 



BY BENJAMIN SILLIMAN, Jr., M. A, 
ii 

PROFESSOR IN YALE COLLEGE, OF SCIENCE AS APPLIED TO THE ARTS. 



WITH MORE THAN TWO HUNDRED ILLUSTRATIONS. 



PHILADELPHIA : 
PUBLISHED BY LOOMIS & PECK. 

BOSTON : CROCKER & BREWSTER. 
NEW HAVEN : DURRIE & PECK. 



1847. 






Entered 

According to Act of Congress, in the year 1846, by 

LOOMIS & PECK, 

In the Clerk's Office of the District Court of Connecticut. 



Peck & Stafford, Printers, 
New Haven. 



TO PROFESSOR SILLIMAN, 

THIS VOLUME, 

DESIGNED 

TO PROMOTE THE CAUSE OF SCIENCE, 

TO WHICH HE HAS DEVOTED HIS LIFE, 

IS RESPECTFULLY DEDICATED, 

BY HIS SON, 



THE AUTHOR. 



PREFACE, 



The object of this work is sufficiently indicated by its title. It has 
grown out of the exigencies of teaching, and has been received as the 
Text Book in the public lectures at Yale College. 

It is important that a work of this kind should contain only such matter 
as is actually taught to a class by recitations and lectures. All fullness 
beyond this is unavailable to either teacher or pupil, and serves often to 
embarrass the one and to discourage the other. This is perhaps the rea- 
son why several works, otherwise excellent, have failed to answer the pur- 
pose for which they were written. The science of Chemistry has now 
reached the point where its First Principles can be presented by 
the teacher with almost mathematical precision. 

Chemistry has attractions of an economical and experimental character, 
which will always secure for it a place in every system of education. 
Without wishing to diminish its claims to attention on these grounds, the au- 
thor urges the paramount advantages possessed by his favorite science, as 
a study peculiarly fitted to train the mind to a methodized and logical 
habit of thought. If nothing more is to be derived from its study than 
the entertainment pffered by brilliant phenomena, and a knowledge of 
convenient economical processes, the pupil will fail of its most import- 
ant advantage. The beautiful philosophy, the perspicuous nomencla- 
ture, and lucid method of modern chemistry, are so obvious that they 
cannot fail to awaken the attention of every intelligent pupil, and carry 
him on his course of intellectual culture with rapid progress. 

With such views the present work has been written. It has been a lead- 
ing object in its composition, not to anticipate the student's acquirements, 
but to carry him forward step by step in a series of consecutive propositions. 
To aid him as much as possible in applying the knowledge already ac- 
quired, the paragraphs have been numbered, and constant reference has 
been made throughout the work to previous sections, wherever the subject 
could be illustrated by so doing. The questions at the foot of each page 
are designed to aid those whose experience in teaching Chemistry may 
not be sufficient to enable them at all times to determine what it is 

1* 



6 PREFACE. 

most important for the pupil to know. The author takes the liberty to 
recommend the free use of the symbolic language of Chemistry, both in 
lectures and in recitations. No other course can so easily familiarize the 
pupil with the atomic numbers and the laws of combination. If the stu- 
dent is accustomed to demonstrate the constitution of bodies on the black- 
board, he cannot long remain in ignorance of the principles of Chemical 
Philosophy. 

The method of this work differs in several features from that which 
is usually pursued in text-books, especially in the order in which subjects 
are discussed, and in the arrangement of the elementary bodies. These 
changes have been made with mature consideration, and in the belief 
that they would aid in communicating a correct knowledge of the subject. 

The author has consulted all the best authorities within his reach, both 
in the standard systems of England and France, and in the scientific 
Journals of this country and Europe. The works of Daniell, Graham, 
Brande, Kane, Fownes, Gregory, Faraday, Mitscherlich, Berzelius, Du- 
mas, Liebig, and Gerhardt, have all been used, as also the treatises of Dr. 
Hare and Prof. Silliman. 

The Organic Chemistry is presented mainly in the order of Liebig in 
his Traiie de Chimie Organique. The author takes pleasure in acknowl- 
edging the important aid derived in this portion of the work from his friend 
and professional assistant, Mr. Thomas S. Hunt, whose familiarity with 
the philosophy and details of Chemistry, will not fail to make him one of 
its ablest followers. The labor of compiling the Organic Chemistry has 
fallen almost solely upon him. 

The author is indebted to Prof. B. Silliman and Mr. James D. Dana, 
for their kindness in revising the sheets of this volume as they passed 
through the press. 

If it shall be found to meet the wants of both teachers and pupils, and 
to promote the progress of Scientific Chemistry in this country, the author 
will feel that he has not labored in vain. 

New Haven, December 1, 1846. 



TABLE OF CONTENTS. 



PART I. 




PHYSICS. 




PAGEJ 


PAGE 


Introduction, . 


13 


Specific Gravity of Solids, 


36 


Sources of Knowledge, 


13 


The Hydrometer, 


39 


General Divisions of 




Specific Gravity of Gases, 


41 


Natural Knowledge, 


14 


Light, Sources and Nature, 


41 


Matter. — General Properties 




Reflection, 


43 


of Matter, . 


15 


Refraction, 


44 


Atoms and Attraction of 




Prism and Analysis of 




Gravitation, . 


16 


Light, . . . 


46 


Indestructibility of Mat- 




Double Refraction and 




ter and Cohesion, . 


17 


Polarization, 


49 


Repulsion and Chemical 




Chemical Rays, 


50 


Attraction, . 


18 


Heat— Sources, . . 52-3 


Elements and Impon- 




Expansion, 


55 


derable Agents, 


19 


Thermometers, 


56 


The Three States of 




Pyrometers, 


62 


Matter — the Solid, 




Laws of Expansion, . 


63 


the Fluid, and the Gas 




Communication of Heat, 


67 


eous, 


20 


Conduction, 


68 


The Atmosphere and 




Convection of Heat, 


71 


Laws of Gases, . 


23 


Radiant Heat, . 


72 


Air-Pump, 


25 


Absorption, 


73 


Law of Mariotte, 


27 


Transmission of Heat, 


74 


Barometer, 


29 


Melloni's Experiments, 


75 


Limits of the Atmos- 




Specific Heat orCapacit} 


,78 


phere, . 


31 


Changfes Produced by 




Weight and Specific 




Heat in the State of 




Gravity, 


32 


Bodies, 


79 


Standards of Specific 




Freezing and Melting, 80 


,81 


Gravity, 


34 


Vaporization, (Boiling 




Specific Gravity of Li- 




Points,) 


83 


quids, . 


35 


Cryophorus, 


88 



8 CONTENTS. 




PAGE 




PAGE 


Elevation of Boiling 


Electricity of Chemical 


Points by Pressure, 89 


Action — Galvanism, 


109 


Evaporation, . . 91 


Voltaic Pile, . 


111 


Diffusion of Gases, . 92 


Electro-Magnetism, 


116 


Dew Point and Hygrom- 


Ampere's Theory, 


118 


eters, ... 94 


Electro-Magnetic Mo 




Spheroidal State of Bodies, 95 


tions. 


121 


Liquefaction of Gases, 96 


Henry's Coils, . 


123 


Electricity. — Of Magnetism, 98 


Secondary Currents, 


124 


Electricity of Friction, 102 


Electro- Magnetic Tele- 




Theories of Electricity, 104 


graph, . . . 


127 


Electrical Machines, 106 


Magneto -Electricity, 


130 


Leyden Jar and Electro- 


Thermo -Electricity, 


131 


phorous, . . 108 






PART II. 




CHEMICAL PHILOSOPHY. 




Elements and their Laws of 


Primary Forms of Crys- 




Combination, . 132 


tals, 


154 


Combination by Weight, 133 


Cleavage and Measure- 




Definite and Multiple 


ment of Crj^stals, 


158 


Proportions, . . 134 


Isomorphism, . 


161 


Equivalent Proportions, 135 


Dimorphism, . 


162 


Table of Chemical 


Chemical Effects of Voltaic 




Equivalents, . 137 


Electricity, 


163 


Combination by Vol- 


Conditions of Voltaic 




ume, . . . 138 


Decomposition, 


164 


Chemical Nomenclature, 140 


Laws of Electrolysis, 


167 


Chemical Symbols of 


Voltameters, 


168 


Elements, . . 144 


Sustaining Batteries, 


169 


Chemical Affinity, . 147 


" " Daniell's, 


170 


Atomic Theory, . 150 


Grove's and Smee's Bat- 




Specific Heat of Atoms, 151 


teries, . 


171 


Crystallization, . . 152| 


Electro- Metallurgy, 


173 



CONTENTS. 



PART III. 



INORGANIC CHEMISTRY. 



PAGE 

Non-Metallic Elements, 175 
Classification, . , 175 

1. Oxygen, . . .176 
Management of Oases, . 179 

2. Chlorine, . . 181 
Compounds of Chlorine with 

Oxygen, ... . 184 

3. Bromine, ... 187 

4. Iodine, .... 189 
Compounds of Iodine with 

Oxygen, &c., . . 190 

5. Fluorine, . . . 191 

6. Sulphur, ... 192 
Compounds with Oxygen^ 193 
Sulphurous Acid, . . 194 
Sulphuric Acid, . . 195 

7. Selenium, ... 199 

8. Nitrogen, ... 200 
Chemical History of the 

Atmosphere, . . 201 
Compounds of Oxygen and 

Nitrogen, ... 203 
Nitrous Oxyd,' . . 204 
Nitric Oxyd, ... 205 
Nitric Acid, ... 207 

9. Phosphorus, ... 209 
Compounds of Phosphorus 

with Oxygen, . .211 
Other Compounds of Phos- 
phorus, . . . 212 

10. Carbon, . . . 214 
Carbonic Acid, . • 218 
Carbonic Oxyd, . . 221 
Other Compounds of Car- 
bon with the Oxygen and 
and Nitrogen Groups, 222 

11. Silicon, .... 223 
Silicic Acid, ... 225 
Fluorid of Silicon, . . 227 

12. Boron, .... 228 
BoracicAcid, . . 229 

13. Hydrogen, ... 230 



PAGE 

Nature of Hydrogen, . 234 
Compounds of Hydrogen, 236 
Water, .... 236 
Eudiometry by Hydrogen, 240 
Union of Hydrogen and Ox- 
ygen by platinum sponge, 242 
Oxyhydrogen Blowpipe, 243 
Natural and Chemical His- 
tory of Water, . . 244 
Peroxyd of Hydrogen, . 248 
Ozone, .... 249 
Action of Hydrogen with 

Chlorine, ... 250 
Hydrochloric Acid, . 251 

Hydrobromic Acid, . 254 

Hydriodic Acid, . .255 
Hydrofluoric Acid, . 256 

Hydrosulphuric Acid, . 257 
Ammonia, . . . 261 
Ammonium and Ammido- 

gen, . . . 264 

Phosphureted Hydrogen, 265 
Light Carbureted Hydrogen, 266 
defiant Gas, . , 268 

Combustion and Structure 

of Flame, ... 270 

Lamps and Blowpipe, 274, 275 

Safety Lamp, . . 277 

Metallic Elements, . 278 

General Properties of the 

Metals, ... 279 
Classification of Oxyds, 282 
Theory of Salts,Salt Radicals,284 
Classification of Metals, 286 

14. Potassium, . . • 287 
Potash, ... 290 
Salts of Potash, . . 293 

15. Sodium and Soda, . . 299 
Chlorid, &c. of Sodium, 300 
Manufacture of Glass, . 304 

16. Ammonium, . • • 305 
Sal Ammoniac, . • 306 



10 



CONTENTS. 



PAGE 

Hydrosulphuret of Ammonia, 307 

17. Lithium, ... 308 

18. Barium, ... 309 

19. Strontium, ... 310 

20. Calcium and Lime, . 311 

21. Magnesium and Magnesia, 314 

22. Aluminium, . . . 316 
Alums, . . . .317 
Pottery, . . .318 

23. Glucinum ; 24. Yttrium ; 25. 
Zirconium ; 26. Thorium ; 
27. Cerium ; 28. Lantanum, 3 J 9 



29. Manganese, 

30. Iron, . 
Manufacture of Iron, 
Oxydsof Iron, 

31. Chromium, 
Tabular View of the Oxyds 

of Manganese, Iron, and 
Chromium, 

32. Nickel, 

33. Cobalt, 

34. Zinc, 



320 
323 
324 
325 
327 



327 
329 
330 
331 



PAGfE 

Cadmium ; 36. Lead, . 332 
Uranium, . . . 334 
Copper, . . . 335 

Vanadium ; 40. Tungsten, 336 
Molybdenum ; 42. Col- 
umbium; 43. Titanium, 337 
Tin, .... 338 
Bismuth, . . .339 
Antimony, . . . 340 
Arsenic, . . . 342 

Arsenious Acid, White Ar- 
senic, . . . 343 
Detection of Arsenic as a 

poison, . . . 345 
Tellurium, . . .347 
Osmium ; 50. Gold, . 348 
Mercury, . . . 349 
Calomel and Corrosive Sub- 
limate, . . . 351 
Silver, . . . . 353 
Palladium,. . . . . 355 
Iridium ; 55. Rhodium, . 356 
Platinum, . . . 357 



PART IV. 



ORGANIC CHEMISTRY. 



Introduction, . . .360 
General Properties of Or- 
ganic Bodies, . . 360 
Compound Radicals, . 362 
Table illustrating the nature 

of Compound Radicals, 363 
Theory of Types and Sub- 
stitutions, . . . 364 
Allotropism of Elements in 

Organic Compounds, . 365 
Isomerism, . . . 366 
Decomposition of Organic 

Compounds, . . 367 
Analysis of Organic Sub- 
stances, . . .368 
Compound Radicals, . . 374 
1. Amide, or Ammidogen, 374 
Compounds of Ammidogen, 375 



2. Oxyd of Carbon, (Ox- 

alyle,) ... 375 

Oxahc acid, . . .376 
Oxalates, , . , 377 

3. Cyanogen, . . . 377 
Cyanic Acid, . .379 
Urea, .... 380 
Fulminic Acid, . . 381 
Cyanuric Acid, . . 382 
Chlorids, &c. of Cyanogen, 382 
Hydrocyanic acid, . 383 
Cyanid of Potassium, &c., 384 
Double Cyanids, . . 385 

4. Ferrocyanogen, . . 386 
Ferrocyanid of Potassium, 387 
Ferrocyanid of Iron, . 387 

5. Ferridcyanogen, . . 388 

6. Cobaltocyanogen, . 388 



CONTENTS. 



11 



7. Platinocyanogen ; 8. Sulpho- 
cyanogen, . . . 389 
Double cyanids of other metals, 389 



9. Mellone, 


. 390 


Uric Acid, 


391 


10. Benzoyle, 


. 393 


Benzoic Acid, 


. 394 


Amygdaline, 


396 


Hippuric Acid, 


397 


11. Cinnamyle, . 


. 398 


12. Salicyfe, 


398 


Salicine, 


400 


Phloridzine, . 


401 


13. Ethyle, Ether, 


401 


Alcohol, 


404 


Nitric Ether, . 


405 


Sulphethylic Acid, 


407 


Olefiant Gas, 


408 


14. Acetyle, Aldehyde, 


409 



Acetic Acid, Quick process, 41 1 
Acetates of Lead, 413 

Dutch Liquid, . . 415 

Action of Chlorine on the 

Ethyle Compounds, . 415 
Chlorids of carbon, . . 415 
Acetone, . . .416 

15. Kakodyle, . . . 416 
Sugars. — Cane Sugar, . 418 

Grape Sugar, . . 419 

Sugar of Milk, Mannite, 420 
Vinous Fermentation, . 421 
Lactic Acid, . . . 423 

16. Methyle, . .^ . 424 

17. Formyle, Formic Acid, . 426 
Compounds with Chlorine, 427 

18. Amyle, Potatoe Oil, . 428 

19. Valeryie, ... 429 
SO.CetyJe, .... 430 
Organic Acids, . . . 432 

Tartaric Acid, . . 433 
Kacemic and Malic Acids, 434 
Tannic Acid, . . 435 
Gallic, Meconic, and Ki- 
nic Acids, Kinone, . 436 
Fatty Substances. — Glycerine, 43 7 
Stearine, Margarine, Ole- 

ine, ... 438 

Soaps, Suberic and Suc- 
ciaic Acid, . . 439 
Falm Oil, Butter, Enanthic 
Acid, Wax, . . 439 



PAGE 

Athamantine, . . 441 
Volatile or Essential Oils. 

Oil of Turpentine, . 441 
Oil of Lemons, Cloves, &c., 442 
Camphor, Oil of Mustard, 442 
Allyle, Oil of Garlic, . 443 
Resins. — Copal, Amber, . 443 
Caoutchouc, or Gum elastic, 444 
Coloring Matters, . . 444 
Quercitrine, Carthamine, 445 
Hematoxyline, Carmine, 445 
Chlorophyle, . . 445 

Lecanorine, Orcine, . 446 
Indigo, . . . 446 

Sulphindigotic Acid, Sax- 
on Blue, . . . 447 
Isatine, Chlorisatine, . 448 
Isatyde, Jndine, Anilic Acid,448 
Carbazotic Acid,Chloranile, 449 
Organic Bases, or Alkaloids. 

Constitution and Characters,450 
Anilene, Conine, Nicotine, 
Quinoleine, Quinine, . 451 
Cinchonine, Morphine, Co- 
deine, Narcotine, . 452 
Strychnine, Brucine, Sola- 
nine, Veratrine, Acon- 
itiae, Sanguinarine, 

Caffeine, Theine, . 453 
Theobromine, . . 454 
Starch AND Allied Substances, 454 
Dextrine, Malt, . . 455 
Diastase, Inuline, Gum, 

Pectine, . . . 456 
Woody Fibre, Lignine, 
Cellulose, . . 457 

Transformation of Woody 

Fibre, . . 458 

Eremacausis, Vegetable 

Mould, ... 458 
Lignite, Coal, Anthracite, 459 
Destructive Distillation of 

Wood, ... 459 
Kreasote, . . . 459 
Eupione, Distillation of 

Coal, ... 460 
Carbolic Acid, Hydrate of 

Phenyle, ... 460 
Kyanol, Leukol, Naph- 
thaline, . . .461 
Petroleum, Naphtha, . 562 



12 CONTENTS. 






PAGE 




TA&E 


Nutritive Substances Contain- 


Nutrition of Plants and An- 




ing Nitrogen, 


463 


imals, 


4,4 


Vegetable Albumen, Fi- 




The Food of Plants, . 


474 


brine, Caseine, &c., 


463 


Cellular Tissue, 


475 


Bread, Yeast, 


464 


Evolution of Oxygen, . 


475 


Animal Albumen, Fibrine, 




Soils, Inorganic Constitu- 




Caseine, . 


464 


ents of Plants, 


476 


Proteine, 


465 


Action of Humus, 


476 


Gelatine, Chondrine, 


466 


Growth of Air Plants, . 


477 


The Blood. 




Fertilizers, Ammonia, Gu- 




Red Globules, Hematine, 


467 


ano, . * . 


477 


Arterial Blood, Chyle, . 


468 


The Digestive Function, 


478 


The Gastric Juice, . 


469 


Assimilation of Fats, . 


479 


Pepsine, the Saliva, 


469 


Waste of Tissues, 


479 


The BiLE.—Cholesterine, . 


470 


Objects of Respiration, 


480 


Choleic Acid and Choleate 


Uses of Oxygen, 


480 


of Soda, . 


470 


Vital Heat, . 


481 


The Urine, . . . 


471 


Balance of Organic Na- 




Calculi, 


472 


ture, 


482 


The Brain and Nervous Mat- 




Appendix, . 


483 


ter, 


472 


Salicine, 


483 


Cerebric and Oleo-phos- 




Gun Cotton, 


483 


phoric Acids, 


472 


Composition of Natural 




Milk and Bones, . 472 


,473 


Waters, . 


484 


Analysis of Bones, 


473 


Index, .... 


486 



ERRATA. 



Note. — Several errors of typography were detected as the sheets passed 
through the press, which will be found in a part only of the edition. 
§ 18, 1. 21,/or '* miles," read " rods." 

§ 42, 1. 12, /or " 2|9;|.i ^2-01,'' read " ||7;||^3.io." 
§ 178, p. 129, I. 17, for "breaking," read " completing." 
§ 225, p. 158, 1. 5, after " oblique rhombic prism," read " or," and omit 

" oblique rhombic," repeated. 
§ 265, 1. 24, /or " Hyperchlorous," read ^^ Hypochlorous." 
§ 307, 1. 14, for " nitric acid," read " nitric oxyd." 
§ 494, p. 290, 1. 5, for " KOCl," read " KCl." 
§ 601, 1. 9, /or " (CO,2Cr03,)" read " (KO,2Cr03.r 
§689,1.14,/or"C32H33''rea(Z"C32H32." 



FIRST PRINCIPLES 

OF 

CHEMISTEY. 

PART I.— PHYSICS. 

INTRODUCTION. 

§ 1 . Sources of Knowledge. — All our knowledge of na- 
ture is the result of experience. Experience informs us that 
like causes always produce like effects. Thus the youngest 
child, when he learns from experience that fire will burn, be- 
comes as truly a natural philosopher as his more advanced 
protector. The merest savage is to some extent a natural 
philosopher. One of the wisest of mankind has described 
man as being " the priest and interpreter of nature."* Every 
experiment is a question addressed to nature, asking for an 
increase of our knowledge, and if we question her aright, 
we shall be sure of a satisfactory answer. 

Observation instructs us in a knowledge of the external 
forms of nature, and we thus acquire our first impressions of 
the various departments of Natural History. 

§ 2. Experiment necessary to increase Knowledge. — Our 
knowledge of natural truths would, however, be very limited, 
without a constant effort to extend our experience by experi- 
ment. The Greeks and Romans were learned and polished 
in all the intellectual arts, and excelled all v/ho have fol- 
lowed them in many branches of human knowledge. Their 
ignorance, however, of the works of nature, and the lawsj by 

§ 1. Name the source of natural knowledge. What has man been 
called ? What is an experiment ? What do we learn from observation ? 
§ 2. How do we enlarge our experience ? How did the knowledge of the 
ancients differ from ours ? 

* " Homo naturce raagister et interpres." — Bacon. 

t By " Natural Laws," or the " Laws of Nature," is meant the order 
of events : e. g., bodies fall to the earth, and water flows down hill, be- 
cause they are under the influence of the law of universal gravitation. 
To ascertain these laws, is one great object of ail science. 



14 INTRODUCTION. 

which they are regulated, was extreme ; and this was be- 
cause they failed to question her aright. The questions of 
the Greeks were addressed to the Delphic oracle^ and not to 
the ready ear of nature. It is highly instructive to us to re- 
member, that there is a great difference between that know- 
ledge which is purely intellectual, and that which we call 
natural knowledge. Speaking of this subject, one of the 
most learned of living philosophers says : " A clever man, 
shut up alone, and allowed unlimited time, might reason out 
for himself all the truths of mathematics, by proceeding from 
those simple notions of space and number, of which he can- 
not divest himself, without ceasing to think ; but he could 
never tell, by any effort of reasoning, what would become of 
a lump of sugar, if immersed in water, or what impression 
would be produced on the eye, by mixing the colors yellow 
and blue." — [Herschel.) 

§ 3. To obtain a correct knowledge of nature in any de- 
partment, it is necessary not only to observe, but also to follow 
up our observation by careful thought. We must never be 
content to hide our ignorance, by substituting a new name for 
what we do not understand ; and we must, from the first, 
learn that nothing is more unwise than to undervalue the 
knowledge we have already acquired, as if it were too trivial 
to be thought of by those who are about to commence the 
study of one of the higher branches of learning. The first 
yound in the intellectual ladder is as important as the last. 

^ 4. General divisions of Natural Knowledge. — The 
great divisions of natural knowledge are, Natural History, 
Mechanical Philosophy, and Chemistry. 1^\\q first teaches 
us the characters and arrangement of the various forms of 
animal and vegetable life and minerals, giving origin to the 
sciences of Zoology, Botany, and Mineralogy. Mechanical 
Philosophy explains the laws which govern matter, with- 
out at all considering of what that matter is composed. It 
tells us how bodies fall to the earth,— ^hqw liquids spout from 
an orifice ; it explains the power of the lever, the screw, 

How did they fail ? What important distinction must we keep in mind 
in regard to knowledge? Give an illustration of this difference. § 3. What 
besides observation and experiment is necessary in acquiring a knowledge 
of nature ? What is said of hiding our ignorance and undervaluing our 
previous knowledge ? §4. Name the three general divisions of natural 
knowledge. What does the first teach ? Mechanical philosophy teaches 
what? 



GENERAL PROPERTIES OF MATTER. 15 

and the inclined plane ; it teaches us the mechanical laws 
of the atmosphere and of the celestial bodies ; but it tells 
us nothing of the nature of the various substances of which 
it treats. Heat, Light, and Electricity, are also branches 
of natural philosophy. 

<§ 5. Province of Chemistry. — Chemistry begins where the 
other natural sciences end. It teaches us the intimate and 
invisible constitution of bodies, and reveals to us the com- 
pounds which can be formed by the union of simple sub- 
stances and the laws of their combination. 

While we now direct our attention to Chemistry, we nat- 
urally inquire, What is Matter ? 

I. MA.TTER, 

1 . General Properties of Matter, 

^ 6. Experience^ founded on the evidence of our senses, 
has convinced us of the existence of matter. We feel the 
resistance which it offers to our touch ; w^e see that it has 
form, and occupies space, and hence we say it has extent ; 
and, lastly, we attempt to raise it, and we find ourselves 
opposed by a certain force which we call weight. 

Matter possesses extension^ because it occupies some 
space. It is impenetrable, because one particle of matter 
cannot occupy the same space with another at the same time. 
It has gravity, because it obeys the laws of universal gravi- 
tation. Whatever, therefore, possesses these three qualities, 
is matter. 

§ 7, Let us look at these qualities a little more attentively. 
The largest and most solid masses of matter, even entire 
mountains, may be ground down by mechanical force to dust 
so fine that the winds will bear it away ; but each minute 
particle still occupies some space, and we may imagine 
that a great multitude of smaller particles may still be 
formed from its further division. A grain of gold may 
be spread out so thin as to cover 600 square inches of 



§ 5. Define the province of Chemistry. What inquiry naturally arises 
In commencing the study of Chemistry? § 6. What evidence have we 
of the existence of matter? What qualities are essential to our idea of 
matter? What is extension ? What is impenetrability? What do we 
ine.ajn by weight? § 7. If we reduce solid matter to dust, do we destroy 
Its quality of extension ? Give .an illustration in the case of gold, of the 
/divisibility of matter,. 



16 MATTER. 

surface on silver wire, and an ounce can be in this man- 
ner made to cover 1300 miles of such wire. One grain of 
green vitriol, (sulphate of iron,) dissolved, and diffused in 
20 million grains of v/ater, will still be easily detected by 
the proper tests. The delicate odor of perfumes, which is 
due to matter in an exceedingly fine state of division, has 
been known to remain for many years in a drawer or apart- 
ment, and still to emit very decided fragrance. Of course 
it had continued to give its appropriate odor during the whole 
time ; and, being invisible at first, we may form some idea 
of the wonderful minuteness of each particle. It is not, 
however, believed that matter is infinitely divisible. 

No better opinion has been expressed on this subject than 
that of the illustrious Newton, who says : " It seems prob- 
able to me that God in the beginning formed matter in solid, 
massy, hard, and impenetrable, moveable particles of such 
sizes and figures, and v/ith such other properties, and in such 
proportion to space, as most conduced to the end for which 
he formed them; and that those primitive particles, being 
solids, are incomparably harder than any porous bodies com- 
pounded of them ; even so very hard as never to wear or 
break in pieces ; no ordinary power being able to divide what 
God himself made one in the first creation.'^ 

§8. Atoms, and Attraction of Gravitation. — These parti- 
cles are called atoms,"^ as expressive of their supposed in- 
divisible nature. They are looked upon as being endowed 
with certain forces or powers, from which we learn the pecu- 
liar character of each. Some view of this sort is required, 
to enable us to understand the various phenomena of chem- 
istry. It will be remembered, however, that we know nothing 
of their size and number, and their properties are in fact all 
that we do know positively about matter, or its existence. We 
know that matter of all sorts is influenced by the laws of uni- 
versal gravitation. It is the constant operation of this law 

Give another illustration in the case of iron. A third case (the perfume) 
is mentioned. Is matter then infinitely divisible ? Give the opinion of 
Newton. § 8. What name is given to the ultimate particles of matter? 
Give the definition. How are these particles or atoms looked on ? What 
is said of our knowledge of these atoms, and of matter itself? What is 
weight? What is the law of gravitation? What does the weight of a 
body depend on ? 

* From the Greek fl, not, and temriQi to cut 



GENERAL PROPERTIES OF MATTER. 17 

on matter which gives to it the property which we call weighty 
which is the measure of the force required to overcome the 
attraction of gravitation. This force, in the language of 
natural philosophy, is said to be directly as the quantity of 
matter, and inversely as the square of the distance. The 
weight of a body is therefore dependent on the number of 
atoms which it contains. 

^9. Indestructibility of Matter.— 'No particle or atom of 
matter can ever be annihilated or destroyed. The same om- 
nipotence which called it into being is required to destroy it. 
But do we not see matter daily perishing before us, in our 
fires, and vanishing in smoke and vapor ? lis forms do in- 
deed vanish from our sight, but it is not lost ; and we shall 
see, when we come to attend to the beautiful phenomena of 
life, by how divine an arrangement the winds and the rains 
gather up their lost atoms, and restore them to the earth, 
thus clothing it in new beauty. 

^10. Cohesion. — The power of gravitation just mentioned, 
acts alike on all matter, and at all distances. But the power 
which holds together the several particles of matter which form 
a solid mass — as a bit of marble or lead — is quite different. 
This latter power is called the force of cohesion, or attrac- 
tion of aggregation,— iYidX power which we must overcome, 
before we can reduce the piece of marble or lead to dust or 
smaller fragments. It is exerted only among particles of the 
same kind, and at imperceptible distances. Opposed to this 
force, which would draw together and keep united all the 
particles of a body, we have the power of repulsion, whose 
tendency is to separate these particles from one another. 

In proof of the first of these powers, if we press together 
two smooth surfaces of lead, clean and bright, as for exam- 
ple the halves of a bullet cut through, we can cause them to 
adhere or unite together so firmly as to require the power of 
several pounds weight to draw them apart. The plates of 
polished glass, also, which are prepared for large mirrors, if 
allowed to rest together, with their surfaces in close contact, 



§ 9. What of the destructibility of matter? What becomes of the 
matter burnt or turned mto vapor? Is it lost ? How shall we prove this? 
§ 10. What other power of attraction is here mentioned ? How diiferiiig 
from gravitation ? Among what particles exerted ? What opposmg force 
have we? Its tendency is what? What example illustrates the attrac- 
tion of aggregation? Another also? 

2* 



18 MATTER. 

have been known to unite so firmly as to break before they 
would yield to any effort to separate them. This is owing to 
the force of attraction between the particles of the same 
kind, called homogeneous attraction, or the attraction of ag- 
gregation. 

§11. Repulsion. — We see the second of these opposing 
powers, namely, repulsion, in one of the common effects of 
Heat. This power is able to unloose the bonds of the 
strongest attraction, and to separate, to a great distance, the 
particles before closely united. Heat will convert ice into 
water, and the water into invisible vapor. The most solid 
metals cannot resist its power ; and yet, when it ceases to 
operate, the antagonist power of attraction again draws the 
scattered particles together, and locks them up in a solid form. 

^12. Chemical Attraction. — Matter is, however, governed 
by another and yet more powerful force of attraction, name- 
ly, the power of affinity, or chemical attraction, . It is unlike 
the power of gravity, because it acts only at invisible dis- 
tances, and is also unlike the power of cohesion, (attraction 
of aggregation,) because it exists only between particles of 
different kinds. Gravity acts on all matter and at all dis- 
tances. Cohesion acts only on the same kind of matter at in- 
sensible distances. Chemical affinity acts only between un- 
like "^d.niclQs at insensible distances. 

^13. The action of this marvelous power of chemical af- 
finity, results in producing from two unlike particles or atoms 
of matter, a third body, having no resemblance in any of its 
properties to either of the other two constituent particles, ex- 
cept that the new body has the united weight of the others. 
To follow out all the wonderful results of this power of affin- 
ity, and make ourselves acquainted with all the new bodies 
which are formed under its influence, constitutes the proper 
business of the chemist. To do this in any degree, we must 
first become familiar with a number of other important sub- 
jects. 

What other name is there for this sort of attraction ? § 11. "What does 
heat show us? How does it act? What changes will it produce on 
water? If removed again, what happens? §12. What other force, still, 
governs matter? Differs from gravity and aggregation in what ? Con- 
trast these three sorts of attraction by their actions. § 13. What is the 
result of chemical affinity ? Has the third body produced the properties 
of its constituents ? What one property of them has it ? What is the 
business of the chemist ? 



GENERAL PROPERTIES OF MATTER. 19 

^14. Elements. — -If we could imagine a v/orld to exist, com- 
posed wholly of lead or of iron, and capable of supporting hu- 
man life, there would be no room for the study of the science 
of chemistry, which owes its existence to the fact that matter 
is various and not simple. We learn not only that there are 
different kinds of matter in the v/orld, but also that nearly all 
the forms in which we see it in nature, or in which v/e make 
it combine by art, are capable of being reduced to a hw sim- 
ple substances, which are called elements. An element is a 
form of matter which has hitherto resisted all attempts to ob- 
tain from it any thing more simple. The number of such bo- 
dies at present known is fifty five, and of these are all things 
made. The progress of science may show us, by improved 
methods of investigation, that some of our elements are com- 
pounds, or, on the other hand, some new ones may be discov- 
ered. Water was one of the four elements of the ancients, 
(earth, air, fire, and water.) We now know that water is a 
compound of two gaseous elements, (oxygen and hydrogen.) 
Gold is an example of what we suppose to be an element. 
We can alter its form by combining it with other substan- 
ces, thus making it part of a new compound ; but no process 
has ever enabled us to show it to be a compound. The pro- 
cess by which a body (as water) is shown to be compound, 
is called analysis ; and that by which the same body is re- 
produced, by the direct union of its elements, is called syn- 
thesis. Where these two modes of proof are united, the 
evidence obtaijied is of the very highest kind. 

§ 15. Imponderable Agents. — Besides the elementary xadXiex 
of the world of which we have already spoken, there are 
certain other agents of so subtle a nature that they seem 
to possess none of the common properties of matter. These 
are Lights Heat, and Electricity ; they are frequently called 
imponderable agents, because we have never been able to col- 
lect and weigh them as we have all other species of matter. 



§ 14. What if the world were made of iron or lead ? To what does 
chemistry owe its existence ? What do we learn of matter? Arc things 
about us generally simple or compound ? In what sense is the term 
element used in chemistry ? Do we positively know any element ? What 
illustration is named of the elements of the ancients? What is gold? 
How can we alter its properties ? What is analysis ? What synthesis ? 
What is the best kind of proof in chemistry? § 15. What other agents 
are there besides those already mentioned ? What have they been called ? 
Why ? They belong to what department ? 



20 MATTER. 

Although we cannot do this, we can show that they are 
in many respects subject to the same laws which regulate 
matter, and it is best to treat of them as if they were so, since 
in that way we can form clearer notions of the beautiful 
laws which govern them. These subjects belong, indeed, 
more properly to Natural Philosophy (^ 4) than to Chemis- 
try ; but some knowledge of them is demanded of the chem- 
ical student at almost every step of his progress, and we 
shall, therefore, say as much of them as will enable the 
learner to understand their chemical bearings. 

2. The Three States of Matter — the Solid, Fluid, and 
Gaseous. 

^16. The three common conditions, or states, in which 
matter is known to us, are the solid, fluid, and gaseous. In- 
deed we may reduce them simply to solids and fluids, if we 
choose to consider fluids as of two sorts, (1) elastic fluids, 
as air and vapor, and (2) inelastic fluids, as water and other 
liquids. We have already hinted that these several states 
of matter are due to the power of heat. (^ 11.) This 
cause will be more fully considered in the chapter on heat. 

§ 17. Properties of Solids. — It is the distinguishing prop- 
erty of solids to have their particles bound together by so 
strong an attraction as in a great measure to destroy their 
power of moving among each other. 

No solid, however, not even gold and platinum, which are 
the most compact solids known, has its particles of matter 
so closely aggregated as to be incapable of some condensa- 
tion. 

Blows, pressure, or a reduction of temperature, will con- 
dense almost all solids into a smaller bulk, and water may 
even be forced through the pores of gold, by very great me- 
chanical pressure. All solid bodies are, therefore, consid- 
ered B,s porous, and their particles are believed to touch each 
other in comparatively few points, having numerous pores or 



Why do we treat of these subjects in a chemical work ? § 16. Name 
the three states of matter. Reduce them to two. Distinguish between 
the two classes of fluids, and give an example. What cause is sug- 
gested for these different states of bodies'? § 17. What is said to be the 
distinguishing feature of solids? What is said of the most compact 
bodies? How can they be diminished in bulk? What proof of the 
porousness of gold ? What of solids in general ? 



THE THREE STATES OF MATTER. 21 

interstices between them, which may in some cases be de- 
tected by the naked eye, and much oftener by a magnifier. 

§ 18. Solids also possess several other properties which 
may be considered in one way or another as modifications 
of the ipowev of cohesion. (§ 10.) (1.) Hardness ; this prop- 
erty is possessed by solids in very various degrees, from 
the diamond, the hardest of all substances, to those solids 
which are so soft as to be easily scratched by the finger-nail, 
as lead and some minerals. Hardness has no connection 
with weight or density, for lead is more than three times as 
heavy as the diamond. (2.) Elasticity ; or the property of 
a spring, of again returning to its original condition after 
being bent. It is found in all degrees of perfection, from 
glass and steel, which are perfectly elastic, to lead, which 
possesses none of this quality. (3.) Brittleness is often 
closely connected with the last property. If glass or steel 
be bent beyond a certain degree, they break suddenly : this 
point is the limit of their elasticity. (5.) Malleability , or the 
capability of being beaten by blows into thin leaves, is found 
in the highest perfection in gold, and in a good degree in 
many other metals ; 300,000 gold leaves may be piled on 
each other and be only an inch thick ; an equal number of 
leaves of common letter paper would be several miles in 
thickness. (5.) Ductility and laminahility are properties 
closely allied to malleability. Iron, for instance, cannot be 
beaten like gold, but it can be drawn into fine iron wire (duc- 
tility) and plated by rollers into thin sheets, (laminability.) 

^19. Fluids' — Fluids are distinguished from solids by 
the perfect freedom of motion among their particles. We 
have said (§ 16) that fluids can be divided into two classes ; 
liquids, like water, and gases or vapors, like air and steam. 
The first are inelastic ; the second highly elastic. We will 
consider them separately. 

§ 20. Liquids press with equal force on all parts of a 
vessel containing them. If an attempt is made to condense 



§ 18. Of what force are the several properties connected in this sec- 
tion modifications ? Enumerate these properties. What is hardness ? 
Give an example. Is it connected with weight or density ? What is 
(2) elasticity? (3) Brittleness? (4) Malleability? Give an example 
and a comparison. (5) How do ductility and laminability differ from 
malleability? § 19. Distinguish fluids from solids. Classify them* 
(^ 16.) § 20. How do liquids press on a containing vessel? 



22 MATTER. 

water, for instance, in a tight vessel, the pressure exerted 
for this purpose will at once be felt in every part of the fluid 
and on all sides of the containing vessel to the same degree, 
as on the portion where the power is applied. Liquids are 
said to be inelastic ; but this is not strictly true, for water 
may be slightly compressed in the refined apparatus of 
CErsted, and the water in a vessel sunk to the depth of 1000 
fathoms (6000 feet) in the sea, has been compressed one 
twentieth part of its bulk. For all practical purposes, how- 
ever, water and other fluids are inelastic, so that they 
may be applied to exert the most resistless power in the hy- 
drostatic press. 

§ 21. Capillary attraction is a property possessed by fluids 
as distinguished from solids. By this property, fluids can 
mount in small tubes (called capillary or hair tubes, from the 
extreme freeness of the bore) to a considerable height against 
the power of gravity. It is this power which enables wood 
and other porous bodies to draw up into their pores any fluid 
with which they may come in contact. Water standing in 
a tumbler always has its surface made concave, being raised 
by capillary attraction at the edges where it comes into con- 
tact with the glass. 

The capillary force is so great, that plugs of dry wood 
driv^en into holes bored for the purpose in rocks, and then 
saturated with water, swell so much from the quantity of 
water drawn into the pores of the wood, (by capillary at- 
traction,) as to burst open the rocks. By the same power, 
a lamp or candle draws up its supply of fuel. Prof. Henry, 
of Princeton, made the curious observation that a solid bar 
of lead bent like the letter U, and one end of it put into a 
vessel of quicksilver, (mercury, which is the only metal fluid 
at common temperatures,) would after some time become so 
saturated with the mercury by capillary action, as to convey 
it out of the vessel, to some degree, as with a syphon. 

When surfaces are wet by water or oil, or any other fluid, 
it is by virtue of this power ; and we see from this that the 



Give an illustration. What is said of the elasticity of liquids? What 
of that of water? How may they be considered, however? §21. 
What is capillarity? Define the word. How is the power seen in a 
tumbler of water ? Also in lamps and candles ? Give an illustration of 
this power in wood. What is said of Prof. Henry's experiment with 
lead ? What is said of the wetting of surfaces ? 



THE THREE STATES OF MATTER. 23 

capillary po\ver is closely connected with chemical affin- 
ity, (or heterogeneous attraction.) Mercury, for instance, 
will not wet or cover the surface of glass or the skin, nor of 
iron ; but it at once wets lead, tin, gold, silver, and many 
other metals. Glass can be wet by water with some diffi- 
culty : oil, however, easily wets glass, and after this, water 
cannot be made to adhere to its surface at all. 

§22. The cohesion of the particles of a liquid for each 
other, is well shown by the globular form of the dew-drop : 
the power of cohesion (or homogeneous attraction) tending 
to unite the drop under the smallest bulk, produces a sphere. 
A soap-bubble is a beautiful example of the cohesive power 
of a thin film of liquid. Soap-water is more viscid but not 
more coherent than pure water, and the bubble may be con- 
sidered as a large drop of water, with all its interior re- 
moved, and the place supplied with air. The cohesive 
power of the particles of water in the film of the bubble is 
so great, that if the pipe be taken from the mouth before the 
bubble leaves it, a stream of air will be driven forcibly 
against the face, (if the bore of the pipe be rather large,) 
from the contraction of the film. Prof. Henry has shown, 
in his ingenious experiments with soap-bubbles, that they 
are by no means toys for children only. 

§ 23. Elastic fluids are either gases or vapors. A gas is 
matter in a permanently aerial form. A vapor is matter 
temporarily in an aerial form. The same physical laws 
govern both, and we will briefly review them. 

It is with some surprise that we first learn that air is as 
truly a material substance as gold and silver, and it requires 
some little reflection to convince us, that our first notions of 
the immateriality of gases are not correct. 

§ 24. The Atmosphere and Laws of Gases. — We on this 
planet live at the bottom of a vast ocean of gaseous matter, 
which we call the air, or " our atmosphere." It surrounds 
us everywhere, and presses upon us with a weight which, 

How is it connected with capillarity ? Give an illustration in mer- 
cury, and in oil and water on glass. § 22. How is the power of cohe- 
sion shown in liquids? What is said of the soap-bubWe 1 Is soap-water 
more coherent than pure water ? How may we consider the bubble ? 
What is said of the cohesive power of the fihn ? How is this well illus- 
trated? §23. What are elastic fluids? (§ 16 and § 19.) Define a gas. 
Pefine a vapor. § 24. To what is the air compared ? 



24 



MATTER. 



when stated in numbers, seems beyond belief. Under its 
influence, all operations, chemical as well as mechanical, are 
performed. It penetrates deeply into the crust of the earth 
itself, and is largely dissolved in all its waters. Its chem- 
ical composition will be discussed in its proper place, when 
we come to consider the properties of the two elements of 
which it is principally composed. 

§ 25. It is usual to speak of a vessel or apartment which 
contains only air, as empty. It is easy to show, however, 
that the so-called empty space is in reality full, and that the 
matter it contains is just as capable of being weighed, trans- 
ferred, and rendered sensible by its resistance to other bo- 
dies, as any other form of matter. If we plunge a bell- 
glass or inverted tumbler into water, holding its mouth hori- 
zontally downwards, we shall find a resistance to its descent, 
which arises from the air confined within it. The water will 
rise in the vessel to a certain height, which varies exactly 
according to the degree of pressure we apply. The deeper 
we sink the glass, the higher will the water rise in its interior, 
and the less space will the air occupy : as we diminish the 
pressure, the air, with the elasticity of a spring, returns to 
its former dimensions, and entirely displaces the water. 

§ 26. Elasticity of the Air. — Suppose the two tight-bot- 
tomed hollow cylinders a and b, in the annexed jSgure, to be 
filled with air : if we fit a plug so 
tightly to the sides of both, that no air 
can press between it and the sides of 
the cylinder, and then try to force 
down this plug by pressure on the 
stem, we shall find a resistance to 
its downward motion. The plug 
(or piston as it is called in the air- 
pump) descends indeed, but with 
increasing resistance as it goes 
down, and if the pressure be re- 
moved, it suddenly and with force 
returns to its former position. We 
have thus demonstrated not only that 
the air is a material substance, of- 



What is said of it ? Is it confined to the surface ? § 25. AVhat is said 
of a so-called empty vessel ? How can we illustrate the presence of air 
in an empty vessel? § 26. Explain the mode by which the elasticity of 
the air is shown in this section. 



THE ATMOSPHERE. 



25 



fering resistance, but also, that it is an elastic substance, 
capable of compression to an indefinite extent, and of restor- 
ing itself to its former condition on withdrawing the pressure. 

§ 27. The elasticity of the air may also be shown by pla- 
cing the piston in h, in the position represented in the draw- 
ing, the air beneath it being in the same state of pressure as 
that above ; if we now attempt to raise the piston, the air 
which before filled only one half of the cylinder, will expand 
and fill the whole ; and this would be the case, if at the 
commencement of the experiment only one thousaniJth part 
of the vessel contained air. The tension, as it is termed, 
would then be only one thousandth part of ordinary air at the 
earth's surface. We thus learn that air and also many other 
gases are perfectly elastic ; although, as we shall see, further 
on, there are a number of gases w^hich can, by great cold and 
pressure, be reduced to a liquid, and some of them even to 
a solid form. 

§ 28. Air-Pump. — The remarks just made serve also to ex- 
plain the principle and construction of the common air-pump, 
an instrument of the first importance to science. In order to 
make an air-pump of one of the cylinders already described, it 
is necessary only to open a 
communication in the bot- 
tom of the cylinder, with 
some vessel from which 
we wish to pump out the 
air, and also to open a hole 
in the piston communica- 
ting with the external air. 
Both of the holes are cov- 
ered with a little door or 
lid of leather or oiled silk, 
fitting the orifice closely, 
and called valves. Both 
these valves open freely in 
an upward direction, but 
the lower one is tightly 




§ 27. How is its elasticity shown in the cylinder h, (§26) ? How does 
half the air fill all the space ? To what extent will this occur ? What 
term expresses the degree of elasticity? §28. What important instru- 
ment do the foregoing principles explain ? How may one of the cylin- 
ders a or 6 (§ 26) be made into an air-pump? Explain the construction 
and use of the same in the figure. 

3 



26 MATTER. 

closed by the least downward pressure. In the annexed fig- 
ure this arrangement is shown. We have a glass vessel, 
(called an air-receiver,) from which it is wished to remove 
the air. It is made to fit tightly by its edges on the metallic 
plate, from which a tube passes forming a connection with 
the bottom of the cylinder, where, as shown in the figure, 
the valve spoken of is placed. Suppose the piston to be 
in the place shown in the figure, and that we attempt to 
raise it by the rod : as it rises, the air beneath it expands, 
to fill the enlarged space, and with it the air in the glass 
vessel and tube also expands, while the little valve at the 
bottom allows the air to pass freely into the cylinder from 
the glass, to supply the vacancy occasioned by the rise of 
the piston. If we now press the piston down, the air beneath 
in the cylinder cannot return into the receiver by the lower 
valve which opens only upward, and, with the least downward 
pressure, closes the opening tight ; but the valve in the piston 
itself now opens outwardly, the air beneath passes out and 
escapes, while the piston descends freely to the bottom of 
the cylinder. We may now raise it again, when a fresh por- 
tion of air will come in from the glass vessel, and be again 
expelled through the piston-valve, when the piston is again 
pushed downwards. By continuing this process, we pump 
out the greater part of the air, as with a common pump we 
draw water from a well. We cannot, however, remove all 
the air in this way, because, as before explained, (§ 27,) the 
smallest quantity of air will expand so as to fill the entire 
space. This process is called exhaustion, 

§ 29. Vacuum. — The space thus produced by exhausting 
the air is called a vacuum, or really empty space ; 3. perfect va- 
cuum, however, cannot be formed in this way, although the air- 
pump can perform an exhaustion w^hich answers all the pur- 
poses of science and art. Many forms of the air-pump are 
in use, all however depending upon the principles explained. 
One of the most common is that in which two pistons are so 
arranged (see fig. in ^ 26) as to work up and down alternately, 
being moved by a winch and toothed wheel. Sometimes the 
cylinders are formed of heavy glass tubes, w^hich enable 



What raises the valves ? On pressing the piston down, why does not 
the air return ? How does the air beneath it escape? What is the pro- 
cess compared to? What is it called? §29. What is the empty space 
called ? Why cannot a perfect vacuum be formed? 



THE ATMOSPHERE. 



27 



the student to see the manner in which the piston and valves 
move, and better to understand the operation. The air-pump 
depends then entirely on the elasticity of 
the air for its successful operation. 

§ 30. Law of Mariotte. — The volume or 
hulk of air then at a given temperature, de- 
pends entirely on the pressure to which it is 
subject, or the volume of the air is always 
inversely as the 'pressure, while the density 
is directly as the pressure. This is called 
the law of Marioite, who was the first accu- 
rately to demonstrate it by experiments. 
The annexed figure shows the simple ap- 
paratus used by him for this purpose. It is a 
glass tube turned up and sealed at the lower 
end : a graduated scale of equal parts is at- 
tached to it. Mercury is poured into the 
open end of this tube so as to rise just to the 
first horizontal line, and a portion of air of the 
ordinary elasticity is thus enclosed in the 
short limb of 9 inches. Now if mercury 
be poured into the longer leg, so that it may 
stand at 30 inches (^33) above the level of the 
mercury in the shorter leg, it will press with 
its whole weight on the included air, which 
will then be found to occupy 4^ inches, 
only half of its former space. If, in like 
manner, the column of mercury be increased 
to twdce this length, its pressure on the 
included air will be tripled, and the space 
occupied by it will be reduced to one third, 
and so on in simple proportion. 

§ 31. Weight of the Atmosphere, — That 
air has weight, has been abundantlj^ shown 
by the experiments already explained. The 
first movement of the air-pump will- fix the 
air-glass on the plate of the pump, and after 
a tolerable exhaustion is produced, great 




§ 30. What is meant by the volume of air ? On what does it depend ? 
State the law in precise terms. What is this law called ? Explain the 
apparatus which illustrates it. §31. How do we know that air has 
weight ? 



28 MATTER. 

force will be required to remove the jar, and the pump itself 
may often be lifted by it. The power that holds the air-jar 
down is only the weight of the air pressing upon the upper 
side of the glass, while that pressure is removed from the 
inside of the glass, by the action of the pump ; an upward 
pressure is exerted also upon the under side of the board or 
plate of the pump, thus cooperating with the downward press- 
ure upon the glass receiver. The leather sucker, as it is 
called, by which boys raise large stones and bricks, acts in the 
same way. The leather adheres to the stone only because 
the air is pressed out from the surfaces of contact, and rests 
with all its weight on the upper side. The labor which we 
perform in raising our feet from a wet clay soil, is due in a 
degree to the same cause ; and if the air could be perfectly 
removed from beneath our feet, w^e should be as firmly and 
immovably planted on the earth as a well-rooted tree. 

The weight of the air is also well shown by the burst- 
ing of a piece of bladder-skin tied tightly over the mouth of 
an open jar on the plate of the air-pump. As the pump is 
worked, the fiat surface of the bladder becomes more and 
more concave, and this increases until the skin bursts in- 
ward with a smart explosion. The same accident would 
befall the glass jars used on the air-pump, if they were not 
made of strong glass, and arched in form. Thin square 
glass bottles are blown purposely, to show this, and burst 
under the air-pump, being either crushed inward by remov- 
ing the air, or burst outward by the expansion of the con- 
tained air, when they are surrounded by a vacuum. 

^ 32. We can also demonstrate the weight of the air by 
exhausting a small glass globe fitted by a stop-cock to the 
pump. Suppose such a globe to hold 100 cubic inches of 
air at the medium temperature and pressure : if we weigh it 
before and also after exhaustion, w^e shall find, if the va- 
cuum be perfect, that it has lost 31 grains of weight, which 
it regains on allowing the air to enter ; hence we learn that 
100 cubic inches of air weigh 31 grains. By using other 
gases besides air, we ascertain by the same experiment 



What force holds down the receiver of the pnmp ? Explain the action 
of the leather " sucker." Why is it difficult to raise our feet in wet 
clay ? Give another experimental illustration of the weight of the air. 
§32. How may we illustrate its weight accurately? How much do 
100 cubic inches weigh? 



THE THREE STATES OF MATTER. 



29 



their relative weights and specific gravities, (§ 49, and figure 
in the same section.) 

§ 33. Barometer. — The Barometer'^ is an instrument by 
which, on principles just explained, we actually 
measure the weight of the atmosphere. This in- 
strument was invented A. D. 1643, by a celebrated 
Italian philosopher, named Torricelli. Philoso- 
phers up to this time had contented themselves 
with saying, when called to explain the phenomenon 
of the atmosphere and the rise of water in a com- 
mon pump, that " Nature ahJiors a vacuum ;" but a 
well-digger in Florence informed Torricelli, that he 
could raise water in a pump only 33 feet, and this 
philosopher at once reasoned, that e/* nature abhor- 
red a vacuum, there was no reason why she should 
cease to abhor it when it was more than 33 feet 
high. He inferred that this column of water must 
be equal in weight to the entire height of the atmos- 
pheric column of equal size. To prove this experi- 
mentally, it was only necessary to use a fluid so 
much heavier than water, as to bring the height 
of the column down to convenient dimensions. 
Mercury was the fluid selected, which is 13 J 
times heavier than water. A strong glass tube 
about 3 feet long, sealed at one end, was filled with 
mercury. The finger being placed on the open end 
as a stopper, the tube was inverted, and the mouth 
immersed in a small vessel of mercury. On with- 
drawing the finger, the mercury in the tube sank a 
certain distance, oscillated up and down, and finally 
came to rest at the height of about 30 inches from 
the surface of the mercury in the outer vessel. 
The empty space above the mercury is the most perfect 




§ 33. What is the barometer ? Give its definition. Who discovered 
it, and when ? What explanation has been before given of atmospheric 
pressure? What observation did the well-digger of Florence make? 
How did Torricelli explain it ? What simple experiment did he choose, 
to prove his inference ? Explain an arrangement of apparatus in the 
figure. What happened in withdrawing the finger ? At about what 
height will the vibrating column of mercury stand? What is the space 
above the mercury called ? 



* From the Greek, haros, weight, and rnetron, measure. 
3* 



30 MATTER. 

vacuum that can be produced, and is called the Torricellian 
vacuum, in honor of the discoverer of the barometer. If 
water were employed instead of mercury, it would require 
a tube about 33 feet long. 

^ 34. Determination of the Pressure of the Atmosphere, — 
The water and the mercury are supported at these respective 
heights by the weight or pressure of the air on the surface of 
the fluid. Such a column of mercury becomes thus an exact 
counterpoise for the weight of the atmosphere. If the tube 
had the area of 1 inch exactly, and the mercury in the 
barometer tube stood at 30 inches, we should find that 
fifteen pounds of mercury would be required to fill the 
tube. The pressure of the air, then, on the surface of the 
mercury, is capable of supporting a column of that metal 
weighing fifteen pounds. This is also the weight of a col- 
umn of air of the same size, and reaching to the supposed 
limits of the atmosphere. Every square inch of the surface 
of land or sea is subject then to a pressure equal to fifteen 
pounds, or to a column of mercury 30 inches in height. A 
man of ordinary size has a surface of about 15 square feet, 
and he must consequently sustain a pressure on his body of 
about 14 tons. This prodigious load he bears about with 
him unconsciously, because the mobility of the particles of 
air causes it to bear with equal force on every part of his 
body, beneath his feet as well as on his head, and in the in- 
ner cavities as well as on the outer surface ; if it were not so, 
great inconvenience and even death must result. We can 
easily feel the pressure of the atmosphere on our own per- 
sons, by placing one of our hands over the mouth of such 
an air-jar as was used in the experiment with the bladder- 
skin, (§ 31,) when a single stroke of the pump will firmly 
fix the hand, which seems drawn in by what we are accus- 
tomed to call suction, but which we now see to be only 
the pressure of the atmosphere. On letting the air in again, 
we cease to feel this sensation, because the balance or equi- 
lihrium of pressure is restored. 

If water were used, how long a tube would be required? § 34. What 
sustains the mercury or water, the tube being open at bottom ? How 
much mercury is a counterpoise to the atmosphere, and in how lonjsf a 
tube, of what diameter? Whence we infer what about the press- 
ure on the surface of every thing? A man sustains what load of air? 
Why are we unconscious of this, and why does it not crush us? We can 
convince ourselves of the reality of this by what simple experiment ? 
What is meant bv what we commonlv call " suctiorC^ ? 



THE THREE STATES OF MATTER. 31 

^ 35. The pressure of the air at the surface is not a con- 
stant quantity. This is shown by the barometer, the mer- 
cury in which will be found to vary in height at different 
times as much as 2 or 2i inches between one extreme and 
another. This variation arises from the fact, that the quan- 
tity of air varies from time to time at the same places, owing 
to meteorological causes which this is not the place, to discuss''; 
but hence arises the value of the barometer as a weather-glass, 
and to show with precision the amount of atmospheric press- 
ure at any given time. The barometer is also of great use in 
measuring the height of mountains ; because it will be seen 
from what has been already said, that the air at the level of 
the sea must weigh more than that on a high hill, since the 
former is pressed down by and supports the weight of the en- 
tire atmosphere, while at the mountain top, it has risen 
above a certain portion of the entire weight of the air. The 
air grows more and more rare as we ascend, and conse- 
quently the barometer falls in exact proportion. People as- 
cending lofty mountains suffer much inconvenience from the 
diminished pressure. The heart continues its action with 
less resistance from the outward pressure of the air, the 
blood flows more quickly, the veins enlarge, and not unfre- 
quently blood starts out from under the nails or from the 
lungs. Any violent exercise or shouting is attended with 
both difficulty and danger. On the summit of Chimborazo, 
Baron Von Humboldt found that his barometer had sunk to 
13 inches 11 lines, and the same gentleman descended into 
the sea in a diving-bell, until the mercurial column rose to 
45 inches ; he consequently has experienced a change of 
31 inches of pressure in his own person. 

Limits of the Atmosphere.— K person who has risen in a 
balloon, or on a mountain, to the height of 2,705 miles, (the 
height of Mount Blanc, about,) has passed through one half of 
the entire weight of th e air, and finds his barometer to in- 

§35. Is the pressure of the air constantly the same? How does the 
barometer show this ? It varies how much ? Arising from what cause ? 
What common name for the barometer is derived from its use? What 
other miportant use is made of the barometer? Whence its use for this 
purpose ? Mention the phenomena observed in ascending high moun- 
tains? From what cause is inconvenience experienced? What obser- 
vations did Humboldt make on Chimborazo ? What depth did he reach 
m the sea ? How many inches of pressure has he personally experi- 
enced ? How high must one ascend in order to pass through half the 
weiijht of the air ? 



32 MATTER. 

dicate this by standing at 15 inches. The upper limits of 
the atmosphere cannot be accurately determined, but it is 
supposed from the observations of astronomers to be about 
45 miles high. We may judge, then, how extremely thin or 
rare the upper portions must be, when we have one half of 
its entire weight within less than three miles of the earth's 
surface. 

3. Weight and Specific Gravity, 

^ 36. At every step of research the chemist must appeal 
to his balances. It is true, the learner in this science has 
little to do with any thing but the results, or the elemen- 
tary facts which have been already worked out for him by 
others. But the weight or density of bodies being so closely 
connected with all their other properties, we shall be well 
employed if we now devote rather more attention to this 
subject than is usual in books of this size. 

^ 37. Density. — The density (or gravity) of a body is the 
quantity of matter within a given space. This is a direct re- 
sult of the law of gravity as already explained, (^8,) the weight 
of a body being the measure of the force of gravity, which is 
directly proportioned to the quantity oi xndXiex . The greater 
the number of particles of a given kind within a given space, 
the greater the density of the body, or in the language of 
common life, the heavier it is. Now as bodies differ greatly 
in this particular, each body is said to have a specific grav- 
ity, or density, peculiar to itself.* 



Where will his barometer then stand ? How high is the atraosphere 
believed to extend? What do we mfer of its rarity in the upper regions ? 
§36. To what instrument does the chemist constantly appeal? §37. 
What is density? What law is it the result of ? (§ 8). The density of a 
body, then, is the measure of what force ? What is the density peculiar 
to each sort of matter called? 



* The balance is the instrument used in these determinations. 
This instrument should possess a beam, inflexible by the weight in- 
tended to be used, and should be delicately poised on a sharp edge of 
hardened steel, (called the knife-edge,) resting on a plate of agate, 
moimted on the summit of an upright pillar of brass. The beam should 
be 60 accurately made that it will assume a horizontal position when at 
rest, its index or pointer marking zero, on the small scale near the foot of 
the column. At each end of the beam is also a knife-edge supporting 
the scale-pan, and in a delicate balance there is always an adjustment 



WEIGHT AND SPECIFIC GRAVITY. 



33 



^38. Specific Gravity. — The specific gravity of a body is 
its weight, compared with that of some other body of ex- 
actly equal volume. We say that lead is heavier than cork ; 
by which we mean, that of equally sized pieces of these sub- 
stances, one is very many times heavier than the other ; that 

§ 38. Define Specific Gravity. What is meant when we say that one 
body is heavier than another ? 




by w^hich, when the instrument is not in use, the beam is supported on 

points independent ^ 

of the delicate i O ' ^^^- ^rjr-rr-^^^:.-^:.-.-.^:^^^^ % 



knife-edge, which 
is thus saved from 
unnecessary wear. 
A good balance 
will turn readily 
with a weight of 
one thousandth 
part of a grain, 
when each arm 
supports one thou- 
sand grains. In 

delicate weighing, a glass case is employed to protect the balance from 
the fluctuations of the atmosphere. When accurate results are required 
with a balance whose arms are of unequal length, or which is from any 
cause inaccurate, the method adopted is to weigh the substance accu- 
rately in each pan, and to take the mean of the two weighings, which 
will give the true weight ; or the substance being placed in one pan, is 
counterpoised accurately by the addition of shot or bits of foil in the 
other : it is then removed, and its place supplied with known weights till 
the equilibrium is restored. The weights added give the weight of the 
substance. 

The figure at the commencement of this note shows the form of a 
good balance arranged for taking specific gravities. One pan is removed 
and a shorter one {h) substituted, from which by a silk thread the sub- 
stance (a) is supported in a glass of pure water, as explained in § 41. 

A person of any mechanical skill can make, with but little trouble 
and care, an instrument which will serve very well in place of a more 
expensive one. For this purpose a thin piece of dry wood is obtained 18 
or 24 inches long, tapered like a scale-beam from the middle to the ends. 
Below the centre of gravity, a delicate sewing-needle is firmly inserted, 
and its ends made to rest on tv/o bits of glass tube of the size of a quill, 
which are supported in the same plane on the opposite sides of a slit cut by 
a saw in an upright of wood which is to be firmly attached to a foot. A 
piece of card-board is inscribed with a scale of equal parts and placed 
at a convenient point on the upright support, and a vertical wire or nee- 
dle carefully inserted in the under side of the beam and at right angles 
with it, so that it will point at zero of the scale when the beam is hori- 
zontal. A needle is also thrust through each extremity of the beam, at 



34 MATTER. 

is, there is very much more matter in the one than in the 
other under equal dimensions. As it is found that a differ- 
ence in specific gravity in bodies, is accompanied by other 
important differences, it is proper to give an account of the 
methods of determining this charact^er. 

^ 39. Standards of Specific Gravity . — Pure water at a 
temperature of 60° is the substance which has been adopted 
as a standard of comparison for the specific gravity of all 
solid and liquid substances ; while the dry atmospheric 
air at 60° of Fahrenheit and 30 inches of the barometer 
is the standard assumed for all gases and vapors. Thus, 
calling water unity, or one hundred, or one thousand, lead 
will be 11-445, or lead is nearly eleven and a half times as 
heavy as water. Cork is lighter than water, and must be 
expressed by a fractional number. Oil of vitriol (sulphuric 
acid) has a specific gravity of 1*847 when pure, or nearly 
twice as much as water. A pint measure of this dense 
liquid would weigh nearly twice as much as a similar 
measure of water ; while a pint of quicksilver would weigh 
thirteen and a half times as much as a pint of water, and a 
like measure of alcohol, only about three quarters as much, 
(0*794 being the specific gravity of alcohol.) We see now 
the necessity of knowing accurately the temperature of 
substances compared at the time of weighing, as their bulk 
increases materially with every increase of temperature, and 
their specific gravity consequently diminishes. 



What is said of the importance of specific gravity? § 39. Name the 
standard adopted for comparison of specific gravity? Of solids and fluids. 
Also for gases and vapors. Mention the examples given in the text. 

points equidistant from the centre, and in the same horizontal line w^ith 
the centra] needle. From these end needles, the pans are supported by 
deMcate silk cords. They may be made of card-board, mica, or sheet 
metal, as may be most convenient. Such a balance, well made, is much 
more delicate for minute weighings, than many of the more complicated 
and expensive kinds, and it possesses the advantage of testing the inge- 
nuity of the teacher or student who is obliged to work without means. 
Small weights are easily made of wire, for which purpose some very del- 
icate wire is to be obtained, and the length of one grain of it having been 
ascertained, it is cut up into decimal parts, and bent into the following 
forms, which simple notation serves to mark them, — J A D 0» 
These figures respectively represent 1, 2, 3, 4, 5, and the size of the 
wire will denote whether they are units, tenths or hundredths of grains. It 



WEIGHT AND SPECIFIC GRAVITY. 



35 




§ 40, Specific Gravity of Liquids. — To measure the spe- 
cific gravity of liquids accurately, a small thin glass bottle 
is required, which should hold a known weight of pure 
water at 60° when accurately filled. One thousand grains 
are a convenient quantity for comparison ; but a smaller quan- 
tity is oftentimes more convenient, when we have but little 
of a substance, although it then requires a simple calcu- 
lation to reduce it to the standard. The accompanying fig- 
ure a shows such a bottle. To its neck 
a glass stopper is adapted, by grinding, 

which is perforated by 

a small hole. The 

weight of the bottle is 

counterpoised by a 

spall mass of lead, 

which is easily cut by 

a knife to the exact 

weight. This coun- 
terpoise is carefully 

preserved for this pur- 
pose. The bottle is now ready for use ; 
it is filled with the fluid under exam- 
ination ; the stopper is carefully introduced, and the excess of 
the liquid gushes out through the small orifice. The exterior 
of the bottle is wiped dry, and its weight, when thus filled, is 
ascertained ; and if the bottle is graduated to 1000 grains of 
pure water at 60°, the weight obtained is the specific gravity. 
For instance, if the fluid is pure sulphuric^ther, the 1000 gr. 
bottle, when filled, would weigh only 720 grains, and -720 is 
the specific gravity of pure ether. As, however, it may not 
be always convenient to procure a thousand-grain bottle, 
any glass phial may be converted into one which will 
answer the purpose very well. Suppose it to contain 376 

§ 40. Explain the method of findmg the specific gravity of fluids, and 
the apparatus figured in this section. If the bottle holds more than lOOO 
grains, what course is adopted ? 

is always assumed, when the weights of substances are stated in books 
of science, that the operation was 'performed at a given temperature 
by the thermometer, and 60° of Fahrenheit's scale is the point agreed 
upon, because that is about the usual temperature of the air ; and if it be 
higher or lower, a corresponding allowance is made, because the bulk 
and consequently the weight of bodies differ with their temperature. 
This precaution is necessary only when we take the specijic gravity of 
bodies, and not their absolute weights. 




36 



MATTER. 



grains of pure water : then, as 376 : 1000, so is the weight 
obtained to the specific gravity of the fluid. A little bottle 
like the annexed cut [b) answers the same purpose, although 
in a less accurate manner than that with the perforated stop- 
per. Its neck is quite narrow, and the lines marked on 
it show the upper and lower surfaces of the liquid in the 
neck. The quantity of pure water which it holds at this 
point is learned from previous trial. 

§ 41. Specific Gravity of Solids. — The determination of 
the specific gravity of solids is founded on the theorem 
first proved by x\rchimedes, that when a solid body is im- 
mersed in water, it loses a portion of its weight exactly equal 
to the loeight of the water displaced. The story in which it is 
stated that this philosopher detected the fraud of King Hie- 
ro's goldsmith, in furnishing to the mona]^, as a crown of 
pure gold, one made in reality of a debased metal, is a 
good example of the practical value of this theorem. In 
fact, plmiging an irregular solid into water, is the only 
mode by which we can easily and accurately measure the 
precise bulk of the body as compared with an equal bulk 
of water. For convenience in taking the specific grav- 
ities of solids, a small scale-pan is hung to one arm of the 
balance, (as shown in note § 37,) and the instrument brought 
to a perfect equilibrium. A hook is attached 
to the lower surface of this pan, for suspending 
a thread. It is required to take the specific 
gravity of the mineral quartz. The specimen is 
attached by a filament of raw silk, or a fine hair, 
witS a noose at the end, to the hook, and the 
actual weight of the mass hanging in the air 
accurately determined. But, in order to have its 
weight as compared with water, we must know 
precisely how much a mass of water just equal 
in bulk to the specimen will weigh. Now if 
we suspend it as it hangs from the scale-beam 
in a vessel of pure water, we shall displace 
just such a quantity of water as corresponds 
with the bulk of the crystals, and no more ; the 
water will buoy up the specimen by a weight 
just equal to a like bulk of water : in other words, the spe- 

^ 41. On what is the method for the specific gravity of solids founded ? 
State this theorem in precise terms. What anecdote is mentioned of 
Archimedes ? How do we proceed in taking the specific gravity of a 
solid ? Why does the specimen weigh less in water ? 




WEIGHT AND SPECIFIC GRAVITY. 



37 



ciraen will weigh less in water than it did in air ; and we 
must diminish the weight on the other side of the beam, to 
correspond with this loss of weight. If we now subtract 
from the weight in air, that which we have found to be its 
weight in water, the difference will evidently give us the 
weight of a bulk of water exactly equal to the bulk of our 
specimen. Now as water is the standard of comparison 
which has been adopted for specific gravity, if we divide the 
actual weight of the substance in air by the weight of an 
equal bulk of water, we shall have the specific gravity sought. 
§ 42. We deduce the following arbitrary rule for deter- 
mining specific gravity. Subtract the weight in water from 
the weight in air, divide the weight in air by the difference 
thus found, and the quotient will be the specific gravity. A 
single example may serve to impress this simple but import- 
ant subject on the mind of the learner : we find on trial that the 

Weight of the substance in air, is 357*95 grs. 

Weight of the substance in water, " 239-41 " 



Difference, 



118-54 



239-41 
118-54 



= 2-01 specific gravity.* 



(p. 



How much less does it weigh? §42. State the rule which is given 
for finding the specific gravity. Give an example on the black-board. 
(Note.) Explain the principles and use of Nicholson's Aerometer. Give 
on tiie board an example of its use. 

* Nicholson^ s Aerometer. — A cheap and convenient substitute for the 
balance is found in a little instrument represented in the annexed cut, and 
called iVic^oZ-soTi's Aerometer, which we will briefly de- 
scribe. ?5 is a metallic ball or float having a descending 
hook, to which is hung a little weighted pan I to hold 
the substance which is weighed in water ; the wire 
stem /supports a cup c. A mark t on the stem show 
the point at which the whole apparatus will float in a tall 
vessel of water when a certain known weight (called the 
balance w^eight) is put in the cup c. The specimen 
under examination must not exceed in weight the bal- 
ance-weight, this being the limit of the instrument. Sup- 
pose the limit to be 100 grains. To find by this instru- 
ment the specific gravity of a substance, place it on c, and 
add weights till the instrument sinks to the mark i : the 
added weight being subtracted from 100, gives the weight 
of the specimen in air. Now place the specimen in the 
pan Z, and again add weights to c. As much more 
weight on c will now be required as corresponds to the 






^-- 






weight of a bulk of water equal io the specimen, which it must be re- 



38 MATTER. 

§ 43. Substances lohich are lighter than water can have 
their specific gravity taken, by attaching to them any con- 
venient bit of metal which will sink them ; the weight of 
the substance is taken in air, and then the united weight, 
after attaching the piece of metal. The weight in water of 
both united is now taken, and the light body being detached, 
the same operation is repeated on the metallic body. 

§ 44. Also, for this purpose, we may take some fluid in 
which the light body will just float, and then determine the 
specific gravity of the fluid by the bottle, (§ 40,) which will 
give us at once the specific gravity sought. Thus, if we put 
a lump of wax into water, it will float above the surface ; but 
in pure alcohol it will sink. If, with care, we dilute the 
alcohol by small doses of water, we shall soon find a point of 
dilution of the alcohol when the wax will just float, or rise 
and sink indifl'erently. The alcohol at this state of dilution 
has the same specific gravity as the wax, and this point we 
may readily find, as suggested above, to be about 0*9. 

h 45. If a substance is in powder or in small grains, its 
specific gravity is found by taking a known weight of it, as 
10 grains, and having introduced it into the specific gravity 
bottle for fluids, to fill it with pure water and weigh : the 
weight of the substance being deducted from the weight of 
the whole contents of the bottle, the diflerence between the 
sum thus obtained and the weight of the water which the 

§43. How can we take the specific gravity of bodies lighter than 
water? § 44. Explain another method by the use of the specific gravity 
bottle, and its principle. § 45. If the substance is in powder, how do we 
proceed ? 

membered is buoyed up by a power just equal to such weight. The dif- 
ference of weight thus foimd will be the divisor of the weight of the spe- 
cimen, and the quotient will be the specific gravity sought. 

This instrument is generally made of brass or tin-plate, but may be 
more elegantly made of glass. 

For example, put the specimen in c. 

Balance weight, lOO'OO 

Weights added to sink instrument to t, 22*57 grains. 



Weight of specimen in air, 77*53 

Specimen placed in lovv er pan requires ad- 
tional weights, 35*43 

35'43--22-57=12-96,theweightof a like bulk of water: then Zli^^ = GOl 

^ ■ 13-96 

the specific gravity sought. 



WEIGHT AND SPECIFIC GRAVITY. 39 

bottle will hold, corresponds with the difference between 
the weight of the substance in air and water. For instance, 
introduce 100 grains of a powdered mineral into a specific 
gravity bottle, holding 1000 grains of pure water, and fill 
the remaining space with water at 60*^. We might expect 
that we should have a weight of 1100 grains, but find only 
1059, the place of some of the water being occupied by the 
powder introduced. 

The bottle holds, 1000 grains. 

Substance introduced weighs, 100 " 

1100 
Weight found, 1059 



Difference, 41 

^ =: 2*044, the specific gravity sought. 

^ 46. If the substance is soluble in water, we must em- 
ploy a fluid of known specific gravity, in which it is not 
soluble. For instance, sugar cannot be weighed in water, 
but in absolute or pure alcohol it can. The specific gravity 
being determined in a fluid whose specific gravity is known, 
as compared with water, it is easy by simple proportion to 
tell the specific gravity of the solid. 

§ 47. The Hydrometer^ is an instrument of great use in de- 
termining the specific gravity of liquids without a balance. It 
is simply a glass tube with a bulb blown on one end of it, 
containing a few shot to counterbalance the instrument, 
while a scale of equal parts is made of paper and introduced 
into the open end, which is then tightly sealed. This 
scale indicates the point to which the stem sinks when im- 
mersed in fluids of different densities. The fluid for con- 
venience is placed in a tube or narrow jar ; the more dense 
the fluid, the less quantity will the hydrometer displace, 
while in a lighter fluid it will sink much deeper, accord- 
ing to its weight. The zero point of the scale is always 

Give the example named in the text on the black-board. § 46. If the 
substance is soluble in water, how do we proceed? § 47. What is the 
hydrometer? Explain its principal use. What is the zero of its scale? 
In case of alcohol how is it graduated? How do we find the true spe- 
cific gravity from the arbitrary scale ? 

* From the Greek udor, water, and metro, I measure. 



40 



MATTER. 



V^^p^ 



placed where the instrument will rest in pure water, after 
which the graduation is effected on a variety of arbitrary- 
scales, all of which can however be referred to the true 
^^.^=-^;5^ specific gravity, by calculation. The 
scales of these instruments read either 
up or down, according as the fluid to be 
measured is either heavier or lighter than 
water. In case of alcohol, (it being lighter 
than water,) the graduation of the hy- 
drometer is made to indicate the number 
of parts of pure alcohol in a hundred 
parts of the liquid, absolute alcohol being 
iOO, and water 0. The hydrometers of 
Beaume (a French maker) are much used 
in the arts. These instruments are of 
the greatest service to the artizan, and 
when carefully made are sufficiently ac- 
curate for most purposes of the laboratory. 
They should always be proved by comparison with the bal- 
ance before they are accepted as standards. For many 
purposes they are made of brass or ivory, as well as of glass. 
^ 48. Little balloons or bulbs of glass are frequently em- 
ployed to find, in a rough way, the density of fluids. When 
several of them are thrown in a fluid of known 
density, some will sink, some rise even with the 
surface, and others will just float. Those wdiich 
just float are taken, and being marked, (as in the 
figure, with the density of the liquid which they 
represent,) are then used to determine the specific 
gravity of liquids of unknown density. They are called spe- 
cific gravity bulbs, and are of great service in ascertaining 
the density of gases reduced to a liquid by pressure in glass 
tubes, when, from the circumstances of the experiment, all 
the usual modes of ascertaining specific gravity are inapplica- 
ble, as will be explained further on. The method noticed in 
§ 44 for finding the gravity of light substances involves the 
same principle as that here given. 




§48. What are specific gravity bulbs? How are they used? Men- 
tion the case in which they are most useful. What previous case ia- 
volves the pnnciple of the bulbs ? 





SOURCES AND PROPERTIES OF LIGHT. 41 

§ 49. Specific Gravity of Gases. — It remains only under 
this head to speak of the modes used for determining the 
specific gravity of gases and vapors. For this 
purpose a globe or other conveniently formed glass 
vessel, holding a known quantity (usually 100 cubic 
inches) by measure, is carefully freed from air or 
moisture, by the air-pump or exhausting syringe, 
and is then filled v^ith the gas or vapor in question, 
as pure as possible, and at 60° Fahrenheit, or 30 
inches of the barometer, (^ 32 :) the weight of the 
apparatus filled with common air being previously 
known, the difference of weight enables the exper- 
imenter to make a direct comparison. The an- 
nexed figure shows an apparatus for this purpose ; 
the globe {b) is provided with a stop-cock, (e,) and 
fitted by a screw to the air-jar (a.) The jar is 
graduated so that the quantity of air or other gas 
entering may be known from the rise of the water in (a.) 
It is thus found that 1 00 cubic inches of pure dry air weigh 
31-0117 grains, while the same quantity of hydrogen gas 
weighs only 2*14 grains, being about fourteen times lighter 
than air. 

II. LIGHT. 

§ 50. The phenomena of light properly belong to the 
science of Optics, a branch of natural and mathematical 
philosophy not closely connected with chemistry. A know- 
ledge of some of the laws of light is, however, required of 
the chemical student, and the progress of discovery daily 
shows us some new connection between the laws of light 
and chemical action. 

§ 51. Sources and Nature of Light. — The sun is the great 
source of light, although we can show also many minor and 
artificial sources. Of the real nature of light we know no- 
thing. Sir Isaac Newton argued that light was a material 
emanation from the sun and other luminous bodies of particles, 
so attenuated as to be wholly imponderable, and having the 
greatest imaginable repulsion to each other. These particles, 

§ 49. How do we find the specific gravity of gases? Explain the ap- 
paratus used. How much do we thus find the air to weigh ? § 50. To 
what branch of science does light properly belong? What is said of its 
chemical importance ? § 51. Name the great source of light. What do 
we know of its nature ? Give the theory of Newton. 

4* 



42 LIGHT. 

by his theory, are supposed to be sent forth in straight lines, 
in all directions, from every luminous body, and falling on 
the delicate nerves of the eye to produce vision. This is 
called the Newtonian or corpuscular theory of light. It is 
not now generally believed to be true, but all the language of 
optics is formed on the supposition of its correctness. The 
other view or theory of light, w^hich is now more generally ac- 
cepted, is called the Wave or Vndulatory theory. It is known 
that sound is conveyed through the air by a series of vibrations 
or waves, pulsating regularly in all directions from the 
original source of the sound. In the same manner it is be- 
lieved that light is conveyed to the eye by a series of un- 
ending and inconceivably rapid pulsations or undulations, 
imparted from the source of light, to a very rare or attenu- 
ated medium, which is supposed to fill all space. This me- 
dium is called the luminiferous ether. However difScult it 
may be to form any just comprehension of the ultimate or 
real nature of light, we do knoio many things about its prop- 
erties, some of which may be enumerated. 

§ 52. Properties of Light. — 1st. Light is sent forth in 
rays in all directions from all luminous bodies. 2d. Bodies 
not themselves luminous become visible by the light falling 
on them from other luminous bodies. 3d. The light which 
proceeds from all bodies has the color of the body from which 
it comes, although the sun sends forth only white light. 
4th. Light consists of separate parts independent of each 
other. 5th. Rays of light proceed in straight lines. 6th. 
Light moves with wonderful velocity, which has been com- 
puted by astronomical observations to be at least one hundred 
and ninety five thousands of 7niles in a second of ti7ne. This 
velocity is so wonderful as to pass our comprehension. Sir 
John Herschel says of it, that a wink of the eye, or a single 
motion of the leg of a swift runner, or flap of the wing of the 
swiftest bird, occupies more time than the passage of a ray 
of light around the globe. A cannon-ball at its utmost 
speed would require at least seventeen years to reach the 

What is this theory commonly called ? What is said of its probability 
and truth? What is the now accepted doctrine? Explain what is 
meant by the undulatoiy theory. What is it which is supposed to undu- 
late ? What name is given to this medium? § 52. State wiiat is known 
of light. 1st. Its rays. 2d. Of its luminousuess. 3d. Of its color. 4th. 
Of its parts. 5th. Of its cause. 6th. Of its velocity. Illustrate this by 
the examples named by Herschel. 



^ REFLECTION. 43 

sun, while light comes over the same distance in about eight 
minutes. 

^ 53. When a ray of light falls on the surface of any body, 
several things may happen. 1st. It may be absorbed and 
disappear altogether, as is the case when it falls on a black 
and dull surface. 2d. It may be nearly all reflected, as from 
some polished surfaces. 3d. It may pass through or be 
transmitted ; and 4th, it may be partly absorbed, partly re- 
flected, and partly transmitted. Bodies are said to be opake 
when they intercept all light, and transparent when they 
permit it to pass through them. But probably no body 
is either perfectly opake or transparent, and we see these 
properties in every possible degree of diflference. Metals, 
which are among the most opake bodies, become partly 
transparent when made very thin, as may be seen in gold- 
leaf on glass, which transmits a greenish purple light, and 
in quicksilver, which gives by transmitted light a blue color 
slightly tinged with purple. To protect pictures formed by 
the daguerreotype process, they are covered with a film of 
gold or copper, so thin as not to injure the impression, and 
yet it eflfectually prevents its removal by the touch. On the 
other hand, glass and all other transparent bodies stop the 
progress of more or less light. 

^ 54. Reflection. — Light is reflected according to a very 
simple law. In the annexed figure, if the ray of light fall from 
P' to P, it is thrown directly back 
to P' ; for this ^reason a person 
looking into a common mirror, 
sees himself correctly, but his im- 
age appears to be as far behind the 
mirror as he is in front of it. If 
the ray fall from R to P, it will 
be reflected to R', and if from 
r, then it will go in the line r', and so for any other point. 
If we measure the angles R P P' and P' P R we shall find 

What is said of the speed of a cannon-ball? § 53. State what be- 
comes of a ray of light falling on any surface. 1st. On a dull surface. 
2d. On a polished surface. 3d. On a transparent. 4th. What else may 
happen? What is a transparent body? What is an opake one? Are 
these qualities ever perfect? What is said of the opacity of gold and 
quicksilver ? Of the silver and copper in the daguerreotype ? § 54. State 
the law of reflection. Draw the diagram on the boaid and deinon- 
Btrate it. 




44 



LIGHT. 



them equal to each other, and so also the angles r P P' and 
P' P r' . These angles are called respectively the angles of 
incidence and reflection. We therefore state that the angle of 
incidence is equal to the angle of refection, which is the law 
of simple reflection. This law is as true of curved surfaces 
as it is of planes, for a curved surface (like a concave metallic 
mirror) is considered as made up of an infinite number of 
small plane$. 

§ 55. Simple Refraction. — If a ray of light falls perpendic- 
ularly on any transparent or uncrystallized surface, as glass 
or water, it is partly reflected, partly scattered in all direc- 
tions, (which part renders the object visible,) and partly 

transmitted in the same direction 
from which it comes. If, however, 
the light comes in any other than 
a perpendicular or vertical direc- 
tion, as from R to A, on the surface 
of a thick slip of glass, as repre- 
sented in the figure, it will not pass 
the glass in the line R A B, but 
will be bent or refracted at A, to 
C. As it leaves the glass at C, it 
again travels in a direction parallel 
to R A, its first course. Refrac- 
tion, then, is the change of direction lohich a ray of light suffers 
on passing from a rarer to a denser medium, and the reverse. 
In passing from a rarer to a denser medium, (as from air 
to glass or water,) the ray is bent or refracted towards aline 
perpendicular to that point of the surface on which the light 
falls, and from a denser to a rarer medium the law is re- 
versed. 

A common experiment, in illustration of this law, is to 
place a coin in the bottom of a bowl, so situated that the ob- 
server cannot see the coin until water is poured into the 
vessel, when the coin becomes visible, because the ray of 
light passing out of the water from the coin, is bent towards 
the eye. In the same manner a stick thrust into water ap- 




What is the angle of incidence? What that of reflection? How 
does this law apply to curved surfaces ? § 55. What becomes of a ray 
of light when it falls perpendicularly on a transparent surface ? When 
obliquely ? Demonstrate it on the black-board from the diagram. Give 
the definition of the law of refraction. Which way is the ray bent ? 
What two common illustrations of this law are named ? 



AMOUNT OF REFRACTION. 



45 




pears bent at an angle, where it enters the water, although 
we know it to be really straight. 

^ 56. Ainount of Refraction. — The obliquity of the ray to 
the refracting medium determines the amount of refraction. 
The more obliquely the ray falls on the surface, the greater 
the amount of refraction. A little 
modification of the last figure will 
make this clear. Let R A, be a 
beam of light falling on a refracting 
medium, it is bent as before to R\ 
If we draw a circle about A as a 
centre, and a line a a, from the 
point a where the circle cuts the 
ray R at right angles, to the per- 
pendicular passing through A, the 
line a a, is called the sine of the angle of incidence ; while 
the line a' a is called sine of the angle of refraction. 

If a more oblique ray r, cuts the circle at b, the line h b, 
will be longer than the line a a, inasmuch as the angle b 
A (2, is greater than the angle a A a. 

The line measuring the obliquity before refraction, when 
the ray passes into a denser m.edium, is always greater 
than that which measures it after, and is nearly one third 
more in the case of water. This is called the index of re- 
fraction, and the refractive power of water is, therefore, 
expressed by the index 1^ or 1*33, while common glass 
with a higher refractive power, has the index of refrac- 
tion H or 1*5, and the diamond 2*439. In the larger works 
full tables will be found with the refractive indices of numer- 
ous substances which are not given here. 

§ 57. Substances of an inflammable nature, or containing 
carbon, and those which are dense, have, as a general thing, 
a higher refracting power than others. Sir Isaac Newton 
observed that the diamond and water had both high refracting 
powers, and he sagaciously foretold the fact, which chemis- 
try has since proved, that both these substances had a com- 



4 56. What determines the amount of refraction ? Show how this can 
be demonstrated bv an alteration of the last figure. What is the line 
a a, called? What is a a, called? What is said of the line jncasuring 
the obliquity before refraction aud after? How much greater in the case 
of water? What is it called? What is the refractive index of water? 
§57. What is said of inflammable substances? Wliat was Newton's 
conjecture about diamonds aiid water ? 



46 



LIGHTc 




bustible base, or were of an inflammable nature. We now 
know that the diamond is pure carbon, and that water has 
hydrogen, a combustible gas, as one of its constituents. 
§ 58. Prism. — In the cases of simple refraction just ex- 
plained, the ray, after leaving the 
refracting medium, has gone on in 
a course parallel to its original 
direction, because the two surfa- 
ces of the medium were supposed 
to be parallel. If, however, we employ a triangular glass 
prism like the figure, or any other surfaces not parallel, the 
ray will be diverted permanently from its original direction 
after leaving the prism. As already explained, the ray R 
is bent towards a perpendicular to the surface, (which is the 
dotted line,) but on leaving the prism it is by the same law 
further refracted in the direction R' ; and by altering the 
form of the surfaces we may thus send it in almost any direc- 
tion, as in the common multiplying-glass, which gives as 
many images as it has faces, and all in different directions. 
In this way it is that concave metallic mirrors accumulate 
and convex ones disperse a beam of light. 

§ 59. Analysis of Light. — By means of the prism we learn 

that a beam of sun- 
light is not simple 
white light, but a 
compound of sev- 
eral colors of the 
most vivid tints 
which can be ima- 
gined. We are also indebted to Sir Isaac Newton for this 
most beautiful experiment, which is called Newton's analysis 
of Light. A direct beam of sunlight from R, in the figure, 
falling from a small circular aperture in the shutter of a 
darkened room on a common triangular prism, is refracted 
twice, and bent upward towards the white screen R', pla- 
ced at some distance from the prism, where it forms an ob- 




What do we now know of them ? § 58. If the surfaces of the refracting 
medium are not parallel, how is the ray affected? Explam this by the 
figure. Give an instance of the application. § 59. What do we learn 
by means of the prism? Who discovered this, and what is it called? 
Explain from the figure how this is done. Is the image on the screen 
round? 



PRISMATIC COLORS. 



47 



RED. SOLAR, SPECTRUM. 




n 



long colored image, composed of sevien colors. This image 
is called the prismatic or solar spectrum, and the light in it is 
said to be analyzed* 

The light from flames of all kinds, the oxyhydrogen blow- 
pipe, and the electric spark, or galvanic light, is also com- 
pound in its nature, like that of the sun and other celestial 
bodies. 

^ 60. Prismatic Colors. — The colors of the solar spectrum 
are in the following order, upwards : red, orange, yellow, 
green, blue, indigo, violet. These colors are of very differ- 
ent refrangibility, and for this reason are presented in a broad 
surface, the red being the least bent and the violet the most. 
Dr. Brewster and many other opticians think that the seven 
colors of Newton are really composed of the three prim- 
itive ones, red, yellow, and blue. This idea is well ex- 
pressed in the following diagram. The three primitive 
colors each attain 
their greatest in- 
tensity in the spec- 
trum at the points 
marked at the sum- 
mit of the curves ; 
while the four other 
colors, violet, indi- 
go, green, and or- 
ange, are the result of a mixture, in the spectrum, of the 
other three. A portion of proper white light is also found 
in all parts of the spectrum, which cannot be separated by 
refraction. We may hence infer that there is a portion of 
each color in every part of the spectrum, but that each is 
most intense at the points where it appears strongest. 

Sir John Herschel has detected rays of greater refran- 
gibility than the violet of the spectrum, which have a laven- 

What name is given to the image ? How many colors are in it? Why 
do we say the light is analyzed? Is light from other sources compound ? 
§ 60. Give the order of the colors in the solar spectrum. Why are these 
colors separated to different parts of the spectrum ? Which is most bent, 
and which least? Give Dr. Brewster's opinion of the seven colors. 
What are the three supposed primitive colors ? Explain the diagram, 
and how the three united form the nine. Is each color pure, or mixed 
with some white light ? When most pure ? 

* The word analysis signifies the separation of a compound into more 
simple parts. 




48 LIGHT. 

der color, and hence are called the lavender rays. They 
have this color after concentration, and are therefore not 
merely, as might be supposed, dilute violet rays. 

§ 61. Natural Color of Bodies. — The colors of bodies in 
nature are supposed to be due to the fact that their surfaces 
absorb all the light, except the color v^e recognize as belong- 
ing to each object, and that this property is due to some 
cause inherent in the nature or state of the substances which 
we do not understand. 

^ 62. Double Refraction, — The sort of refraction {simple 
refraction) which we have just considered, belongs to all 
bodies which permit the passage of light. But in most 
crystalline substances, and all bodies having any regular in- 
ternal structure, such as bone, shell, &c., there is another 
sort of refraction. By looking through such bodies in cer- 
tain positions, two objects are seen instead of one ; one by 
the ordinary, and the other by an extraordinary refraction. 

This is called Double refraction, and is best seen in the 
common mineral called calc spar, or Iceland spar, which, 
when pure, is colorless and transparent, and breaks with 
brilliant faces into regular rhombs. If a rhomb of this min- 
eral be laid over a black line, we see a double image as dis- 
tinct as if there were in reality two lines.* This direction 
of the ray is owing to the interior crystalline structure of 

§ 61. Give the cause of the color of natural bodies. § 62. How g-en- 
erally is simple refraction found in transparent bodies ? What bodies have 
another sort of refraction ? What is seen on looking through such bodies ? 
What is this property called? In what best seen? What is this property 
owing to ? Explain the figure in the note, on the board. 

* A sharp line like p q^, when seen through a rhomb of calc spar in 
the direction of the ray R r, will seem to 
be double, a second parallel line m n, being 
seen at a short distance from it, and the 
dot 0, will have its fellow e. In this case 
the light is represented as coming from R to 
r, and passing through the crystal, it is split 
and emerges in two beams at e and o. The 
same effect would be produced if the light 
fell so as to strike any part of the imaginary 
plane A C B D, which diagonally divides the crystal, and is called its 
principal section. The axis or line drawn from A to B, is contained in 
this plane. But if we look through the crystal in a direction parallel to 
this plane (A C B D) there is only simple refraction, and only one line is 
seen. 




CHEMICAL RAYS. 



49 



the mineral. Of the two beams into which the light is di- 
vided, one obeys the law of refraction already explained, 
while the other pursues an entirely different course. One 
is called the ordinary, and the other the extraordinary ray. 

^ 63. Polarization. — The light which has passed one crys- 
tal of Iceland spar by extraordinary refraction, is no longer 
affected as is common light. If we attempt to pass it through 
another crystal of the same substance, there will be no further 
subdivision, and only a greater separation of the two beams. 

This peculiar physical change is called polarization* 
Many other mineral substances also polarize light when 
cut into thin plates. The mineral called tourmaline has this 
property in a remarkable degree. Polarization is said to be 
owing to the production of" opposite properties in opposite di- 
rections, so exactly equal as to be capable of accurately neu- 
tralizing each oth- 
er." In the an- 
nexed figure we 
have two thin 
plates of the min- 
eral in question, 
[tourmaline,) pla- 
ced parallel to 
each other in the same direction. A ray of light passes 
through both in the direction oi R R\ and apparently suffers 
no change : if, however, these plates are so placed as to cross 
each other at right angles, the ray of light is totally extin- 
guished ; and four such points may be found in revolting one 
of the plates about the ray as an axis. 

^ 64. The same effect of polarization is 
produced by reflection from various substan- 
ces at an angle peculiar to each substance, 
and therefore called the angle of polarization ; 
and which for glass is found by experiment to 
be 56° 48'. Several plates of thin glass po- 
larize light very powerfully when arranged 
as in the figure, from 12 to 20 plates being 
placed in a bundle. Some of the most splen- 
did experiments and exhibitions in optics 

§ 63. Explain polarization by the change produced on a fay of light by 
certain minerals. § 64. How is it produced by glass, and at what angles? 






* The light is supposed to assume a polar arrangemeiTt. 
5 



50 LIGHT. 

are made with polarized light ; it brings forth combmatioTis 
of prismatic colors and hues, quite surpassing all that we 
have before known. It has also opened a field of investiga- 
tion fruitful in scientific and practical results, any further 
notice of which, however interesting, would lead lis away 
from our present object. 

^ 65. Chemical Rays. — Besides the rays of light in the 
solar spectrum which we have already noticed, and the rays 
of heat which we shall presently consider, there is still an- 
other class of rays, which, while they have a greater refran- 
gibility than the violet, are also found by the delicate exper- 
iments of Herschel, to be present in every part of the solar 
spectrum : they have been sometimes called the chemical 
rays, from the powerful effect which they produce in chem- 
ical combinations. They act in a manner altogether inde- 
pendent of the rays of heat, and, if we can conceive of such 
a thing, are, in fact, invisible light. Chlorine and hydrogen 
gases are made to combine by them with explosive energy, 
while in diffuse light the union of these gases is slow and quiet. 
The bleaching power of the sun's light is also due to the 
chemical rays. Salts of silver and many other substances are 
decomposed by them, giving origin to the beautiful art of 
photography. The Daguerreotype plates and photographic 
papers are affected by them.. The great attention which this 
class of phenomena has received for some time past has, 
indeed, created a new department of science.* 

The accompanying diagram will enable the student to ob- 
tain clearer notions of the views at present in vogue on this 
interesting and important department of scientific inves- 
tigation, which has already made so many splendid pres- 
ents to the arts. From A to B, we have the solar spec- 
trum with the colors in the same order as already descri- 
bed, (§ 60.) At the violet is the greatest chemical power, 
and the greatest heat is found at the red. At h another red 
ray is discovered, and at a is the lavender light. The lumin- 

§65. What are the chemical rays? Name some of their effects. 
What arts are dependent on them? 

* Dr. Draper has proposed to call these rays Tithonic, and their in- 
fluence on chemical action, Tithonicity. Mr. Hunt, an English inves- 
tigator, would call them jEJ/ier^za. The term, however, which is most 
likely to be used, as involving the least conjecture, is Actinism and the 
dep'jrlmont of -Chemistry to which they give rise, Actino-Cheraistry ; this 
term isfroiif the Greek, aciin, a ray. 



LA.TENT LIGHT. 



51 



EXTREME RED b 



ous effects are shown by the curved line C, the maximum of 

light being found at the yellow ray. The point of greatest 

heat is at D, beyond the red 

ray, and it gradually declines 

to the violet end, where it is 

entirely wanting, the other 

limit of heat being at c. The 

chemical powers are greatest 

about E, in the limits of the lavender, 

violet, and gradually extend violet, . 

to d, where they are lost, indigo, . 

They disappear also entirely ^^^^ 

at C, (the yellow ray, which 

' ^ , y , . -^ ' V GREEN, . 

is neutral m this respect,) at- 
tain another point of consider- y^^^^^^' 
able power at F, in the red orange, 
ray, which gives its own color ^°' 
to photographic pictures ; and 
ceases entirely at e. The 
points D, C, E, therefore, rep- 
resent respectively the three 
distinct phenomena of Heat, 
Light, and ,Chemical Power, ^' 

or Actinism, (see note.) This last is believed to be quite in- 
dependent of the other powers ; for all light may be removed 
from the spectrum by passing it through blue solutions, and 
yet the chemical power (or actinism) remains unaltered. 

§ 66. Latent Light. — In connection with the chemical 
properties of light, we must mention the curious facts no- 
ticed and illustrated in this country by Dr. Draper, and in 
Europe by Mr. Moser ; that bodies have the power of im- 
pressing their images or pictures on each other in the dark, or 
on plates of polished metal and glass, in such a manner that 
these become at once visible, if the bright surface be breath- 
ed on or mercurialized. If a coin or medal be placed on a 
finely polished surface of sheet-copper or silver, and be left 
in a perfectly dark place for a few hours, particularly if the 
plate has been warmed, it will be found that on breathing 
upon or mercurializing the metallic surface, an image 




Explain the diagram, showing the points of light, heat; and chemical 
action. § 66. What is latent light? Name the curious effects produced 
by it. 



52 HEAT. 

of it will at once be brought out, and can be renewed in 
the same manner indefinitely. It is supposed that this eiFect 
is owing to latent or invisible light, passing between the two 
surfaces, and producing a change in the condition of the sur- 
face, or the arrangement of its particles. Engravings can be 
permanently copied in this way, and many curious and in- 
structive experiments performed, which our space will not 
permit us to describe. 

§ 67. Phosphorescence is a property possessed by some 
bodies of emitting a feeble light, at a temperature too low 
to allow us to suppose that the light is due to ignition. The 
diamond, after being exposed to the rays of the sun, will 
phosphoresce (emit light) for some time in the dark. 
Fluor-spar, feldspar, and many other minerals, give out a fine 
light of varied hues, when gently heated. The glow-worm, 
the fire-fly, rotten wood, decaying fish, and various marine 
animals, possess the same property in a greater or less degree. 

§ 68. Light, as it comes to us from the sun, is (as we have 
before said) accompanied also by heat. Indeed, it seems 
not too much to believe, that light, heat, chemical action, 
and electricity, are only modifications of one and the same 
power or force ; and the recent researches of Dr. Faraday 
in the magnetization of light, go far to prove, by experiment, 
the truth of this opinion, which has been long held by many 
philosophers. 

III. HEAT. 

§ 69. All our knowledge of heat is confined to its effects. 
We experience a sensation on coming near to, or touching 
other bodies, which we call heat or coZc?, according as they 
have a higher or lower temperature than ourselves. This 
is the common use of the word. In chemical language, we 
mean by heat, the unknown cause of the effects produced 
by it on bodies, and not the sensation. We are as ignorant 
of the real nature of heat as we are of light. It is often 
called " one of the imponderable agents," because we can 
find no increase of weight in bodies by heating them never 
so much, nor any decrease in weight by cooling them. The 

§ 67. What is phosphorescence ? § 68. What is said of light, heat, and 
electricity, in this section? § 69. What do we know of the nature of 
heat ? 



SOURCES OF HEAT. 53 

changes which heat has power to work on matter are won- 
derlul, and as it is one of the most important of chemical 
agents, we shall be well employed in the study of its phe- 
nomena. 

Without pausing, therefore, to consider any of the ingen- 
ious theories which have been proposed regarding the na- 
ture of heat and its relations to matter, we will proceed at 
once to study its effects. 

^ 70. Sources of Heat, — 1st. The sun is the great source 
of heat. His rays alone make the earth inhabitable ; without 
them, this world would be only a barren waste, and its waters 
would be as solid and unalterable as granite. All the com- 
bustible material on or in the earth, would not supply the 
want of the sun for a single day. 

2d. Combustion is another source of heat. Our fires give 
us warmth, because the combustible part of the fuel takes 
on a new form of existence, being chemically combined 
with one portion of the atmosphere, and heat is evolved. 
This source of heat, then, is due to a change of state in 
bodies. 

The same cause we shall also see, further on, {^ 111,) may 
sometimes be a source of cold, that is, of a diminution of 
heat. This source of heat is entirely limited by the amount 
of substance suffering change, and ceases when the change 
is complete. 

3d. Friction is a third source of heat. Heat is generated 
by friction to an indefinite amount, by the motion of one 
body on another ; as the rubbing together of two limbs in a 
forest, moved by violent winds, by which it is said, that so 
much heat has been excited as to set fire to large tracts of 
timber-lands. Savage nations, by rubbing two sticks vio- 
lently together, are accustomed to produce fire. Large plates 
of iron have been made to move slowly over each other, by 
water-power, and have thus produced so much heat as to 
warm extensive buildings. The water beneath which cannon 
are bored, becomes very hot, from the friction of the borer 
against the metal which it cuts. The principal thing to be 
remarked in reference to this source of heat is, that it 
seems to be without limit, so long as motion is continued ; 
and that the substances used to produce friction, do not ne- 

§ 70. Name the sources of heat ; 1st. What is said of the :2d, and its 
peculiarity ? What is pecuhar about the heat of friction 7 



54 HEAT. 

cessarily Buffer any permanent change of state. The evolu- 
tion of heat goes on, the substances acted on neither in- 
creasing nor diminishing in quantity, while the body retains 
its chemical properties unaltered. 

4th. A fourth source is Electricity, and it is probably very 
closely allied to the second. The spark from the electrical 
machine, the galvanic current, and the forked lightning, are 
alike sources of heat. 

We might also mention the warmth of our own bodies, 
and the whole animal world, as another source of heat ; but 
it seems more than probable that animal heat is only the 
result of chemical changes going on in the process of res- 
piration, and the other functions of the body, and as such, 
belongs to the second source, already mentioned. 

5th. Geology has taught us, that the interior of the earth is in 
a state of intense ignition, amounting at times to fluidity, as 
is proved by the eruptions of lava from active volcanoes. 
All the excavations for mines and artesian* wells which have 
been made, have shown, that as we descend, the temperature 
of the earth constantly increases, after we have passed 
below the influence of the atmosphere. This increase 
amounts to about 1° of Fahrenheit's thermometer for every 
40 or 45 feet of descent. The celebrated well at Grenelle, 
near Paris, (which is an artesian boring,) is 1794 feet deep, 
and its temperature is 82°, which is 31° above the mean tem- 
perature of Paris ; and the well at Mondorf is 2200 feet deep, 
and the water rises with a temperature of 95° Fahrenheit. 
This increase of temperature, if continued at the same rate, 
would give us boiling water at about two miles from the sur- 
face. At ten miles, all substances would become intensely 
red ; and at thirty or forty, all known bodies would be in a 
state of fusion. No doubt the central heat of the earth, es- 
caping by insensible degrees to the surface, has had an im- 
portant influence on its condition. 



What is said of electricity and animal heat? What is said of the cen- 
tral heat of the earth ? State the facts. Does heat from these various 
sources differ in kind ? 



* Artesian wells are borings made with an auger, usually to a great 
depth, and are so called from the province of Artois in France, where 
they were fiist made. 



EXPANSION. 55 

From whatever source heat may be derived, its effects on 
matter are the same, and we will consider one of its most 
general powers, namely, — 

1. Expansion. — The effect of Heat in altering the dimensions 
of Bodies, 

§71. Heat has been called the antagonist of attraction: 
while the latter power acts to bind together the particles of 
matter, heat tends to separate them. We see about us mat- 
ter in the different forms of solids, liquids, and gases or vapors. 
Water presents a familiar instance of a substance known to 
us in all three of these states ; as a solid in ice, a liquid 
at common temperatures, and an invisible vapor at higher 
temperatures. The sole cause, so far as we know, of this 
change of state in water, is variation of temperature. 

§ 72. We have before seen (§ 26) the remarkable power 
of elasticity in expanding air and other gases. Heat produces 
expansion in all bodies, even the most firm. The change 
of dimensions, under the influence of heat, is so powerful 
as to set at defiance all attempts to restrain it. 

^ 73. To show the expansion of a solid, a bar of metal 
is provided with a handle, (see an- 
nexed figure,) which, at ordinary tem- 
peratures, will exactly fit a gauge : 
on warming this over a spirit-lamp, 
or by plunging it into hot water, 
it will be so much swelled (expanded) 
in all its dimensions, as no longer to 
enter the gauge. On cooling it with 
ice, it will not only again freely enter, f^''''''''''''"'''^'''i''MMP 
but with room to spare. The same ^ 

fact is shown by a small cannon-ball, I ^- 

to which, when cold, a ring with a 

handle will exactly fit, but on heating the ball in the fire, the 

rinQ[ will no lonorer encircle it. 



§71. Of what is heat the antagonist force? Illustrate this. §72. 
What power of heat do we now consider? §73. Illustrate this in a 
solid. 



56 



HEAT. 




§ 74. The expansion of a fiuid may be shown by plun- 
ging the bulb of a large tube a, as in 
the annexed figure, filled with col- 
ored fluid to the line marked on the 
stem, into hot water ; the fluid is 
seen to rise rapidly in the stem. If 
it be cooled by a mixture of ice and 
water, it is seen to sink considerably 
below the line. A similar bulb 6, filled 
with air, and having its lower end 
under water, is arranged as in the 
figure to show the expansion of air 
by heat. The warmth of the hand 
applied to the naked ball will be 
sufficient to cause bubbles of air to 
escape from the open end through the water, and on re- 
moving the hand, the contraction of the air in the ball, 
from the cooling of the surface, will cause a rise of the fluid 
in the stem, corresponding to the vokune of air expelled, as 
shown in the figure. The slightest change of temperature 
will cause this column of fluid to move, as the air expands 
or contracts. We thus prove experimentally that solids, 
fluids, and gases, all expand by increase and contract by de- 
crease of temperature. 

^ 75. Thermometers. — The law of expansion, as just ex- 
plained, enables us to construct an instrument by which 
we can measure or estimate changes of temperature with 
accuracy. Such an instrument is the Thermometer, or 
measurer of temperature. Hot and cold are terms of com- 
parison only, and teach us nothing of the real difference 
of temperature which bodies may possess. If we place 
one hand in a vessel of iced water, and the other in mod- 
erately warm water, we at once perceive a strong contrast ; 
but if we suddenly plunge both hands into a third vessel 
of water at the common temperature, our sensations are 
at once reversed, the third vessel is warm as compared 
with ice-water, and cold as compared with the tepid water. 
The thermometer, however, enables us with the greatest 



§ 74. Illustrate expansion in a fluid ; (a) in water, (h) in a gas. 
§75. What instrument does the law of an expansion give us? What 
does this instrument enable us to do? Illustrate the inaccuracy of our 
sensations. 




EXPANSION. 57 

ease to obtain accurate notions of these comparative tem- 
peratures. 

This valuable instrument was first constructed by Sanc- 
torio, an Italian philosopher, about A. D. 1590. Sancto- 
rio's instrument was what is now called an air- ^-^ 
thermometer, because a confined portion of air was 
employed, to show the changes of temperature. 
The annexed figure shows the arrangement of the 
parts. A bulb of glass with a long stem was in- 
serted by a cork, mouth downwards, in a foot-ves- 
sel containing a portion of colored water. A part 
of the air was expelled from the ball by expansion, 
(^ 74,) which caused the fluid to rise to a convenient 
point in the stem, to which was attached a scale of 
equal parts, with degrees or divisions marked by 
some arbitrary rule. Thus arranged, the instrument 
indicated with great delicacy any change of temper- 
ature in the surrounding air. The portion of air 
confined in the ball, when heated in any degree, would ex- 
pand, and pressing on the column of fluid in the stem would 
drive it down, according to the amount of expansion or the 
degree of heat ; and the reverse resulted from a decrease 
of temperature, the confined air then contracting occupied 
less room, and the fluid rose. The air-thermometer is very 
delicate, but is too limited in its range to supply the wants 
of science ; it has given place to the — 

§ 76. Mercurial, or common thermometer, which is now 
in every house. This instrument indicates changes of tem- 
perature by the expansion of a fluid in a vacuum, and is 
capable of showing all the ordinary changes. It is formed 
of a small glass tube with a very fine bore, (a capillary 
tube, § 21,) on one end of which is blown a small ball or 
bulb to contain the mercury, or other fluid with which it is 
filled. This instrument is made by a process which gives 
us a fine illustration of several principles already explained, 
which we will briefly describe. 

It would be impossible to pour any fluid (much less, mer- 
cury) into so small an opening as the fine hair-line of a 
thermometer-bore. If, however, we cautiously hold the ball 
of the tube in the flame of a small alcohol-lamp, the heat. 

Who invented the thermometer, and when ? Explain his instrument. 
§76. What instrument is now used in place of the air-thermometer? 



58 HEAT. 

expanding the air which it contains, will drive out a por- 
tion of it at the open end, which is held under the sur- 
face of a small quantity of mercury, and the air will be 
seen escaping in bubbles through it. Let us hold the 
tube as nearly horizontal as possible, and, still keeping its 
open end under the mercury, withdraw the ball from the 
heat ; as it gradually cools, the contraction of the remain- 
ing portion of the air within the ball, (§27,) aided by the 
pressure of the air on the surface of the mercury, (§ 33,) 
will cause the fluid to rise rapidly in the tube, and we shall 
presently see it fall, drop by drop, into the empty ball, until 
(if the process has been well performed) it is nearly filled. 
How shall we get rid of the remaining air in the ball and 
tube? Let us fit a small funnel or cone of paper to the 
open end of the tube, tie it securely there, and put it into 
a little mercury, which will quite cover the open end. We 
will now place the ball in the lamp-flame again, and taking 
care not to heat the stem, we will cautiously warm the mer- 
cury, until the heavy fluid boils vigorously in the delicate glass 
ball. The air in the tube is driven out by the vapor of the 
boiling mercury, and we see it escape in bubbles through the 
fluid metal in the paper funnel, which acts as a valve (§ 28) to 
prevent its return. The whole space is now full of the 
invisible vapor of this dense metal, and once more with- 
drawing the ball from the heat, the vapor is condensed, and 
the pressure of the air on the surface of the mercury in the 
funnel, instantly forces it into the vacuous cavity beneath, 
completely filling both ball and stem. The operation of 
thermometer-making is now completed by once more warm- 
ing the ball, to expel any lingering portion of the air, and also, 
if necessary, a part of the mercury in the stem, and at the 
same instant the open end of the tube is sealed by a blow- 
pipe. On again cooling, the mercury contracts, and leaves 
a vacuum of the most perfect description, {§ 33.) We will 
explain presently how our thermometer may be fitted with a 
scale.* 

Alcohol is also employed to fill thermometers which are 
to be used for estimating very low temperatures. But mer- 

Give the process of making a thermometer. 

* The teacher should by no means lose the opportunity of perform- 
ing this simple but instructive operation in presence of his pupils ; it can 
be done in a little more time than it requires to explain it, and its interest 
will not be diminished by an unsuccessful attempt. 



EXPANSION. 59 

ciiry is the fluid preferred for all common cases, because 
of the great uniformity in its rate of expansion. 

In the arctic regions, the temperature is, for many weeks 
together, below the freezing-point of mercury, and here al- 
cohol thermometers are indispensable. Pure alcohol has 
never been frozen. 

^ 77. Graduation of Thermometers. — To make the ther- 
mometer of any value as an indicator of temperature, we 
must have a standard of comparison, by which two observers, 
with different instruments, and in different parts of the globe, 
may compare the results of their observations. We are 
indebted to Sir Isaac Newton, again, for the method of 
graduating thermometers. He knew that ice melted, and 
water boiled, always at the same temperatures at the 
level of the sea. By marking the points where the mer- 
cury of a thermometer stood, in boiling water, and also the 
point in a mixture of snow or ice with water, two fixed and 
immutable points are obtained, the boiling and freezing of 
water,* which were found, by repeated trials, to be at the 
same relative distance in all good instruments. By dividing 
the space between these points into any number of equal parts, 
the instrument became complete, and its indications could be 
compared with those of any other, made on the same plan. 

^ 78. Thermometrical Scales. — The indications of the 
thermometer are interpreted in different ways by different 
nations. In this country and in England, Fahrenheit's scale 
is chiefly employed. It is unfortunate that there should 
be more than one sort of scale in use, because it obliges us 
to stop and translate the terms of any other nation into our 
own. The scale or division of Celsius [a. Swedish philoso- 
pher) is generally used at present in continental Europe, and 
is also called the Centigrade scale, because it divides the in- 
terval between the boiling and freezing of water into one 
hundred parts. Formerly the French used the graduation of 
Reaumur, which made 80° between boilincr and freezinof wa- 
ter. Fahrenheit (who was a citizen of Amsterdam) thought 

§ 77. How is a thermometer graduated ? § 78. Name the principal 
scales in use. What number of degrees did Celsius make, between boil- 
ing and freezing water? How many are there in Reaumur's scale? 

* We shall see hereafter that, although the melting and freezing of 
water take place at the same temperature, under favorable circumstances, 
yet that it is the laelting of ice, and not the freezing of water, which 
gives invariabl)' the constant temperature of 3:2° — the freezing point be- 
ing liable to some variation. 



60 



HEAT. 



2J0-E~- 



180 



m- 



that he had found the true zero, or point of greatest possible 
cold, by an artificial mixture of snow and salt, below which 
it was impossible for any temperature to fall. We now know 
that there is no such thing as an absolute zero,* either of heat 
or cold, and that it is highly unphilosophical to 
suppose such a thing. Fahrenheit divided 
his scale from his supposed zero to the boil- 
ing point of water into 212°, which places the 
freezing of water at 32°, and leaves 180° 
between that point and the boiling of wa- 
ter. Both Celsius (Centigrade) and Reau- 
mur made the freezing of water the zero of 
their scales. The degrees of Centigrade 
are always marked in books C. ; of Reaumur 
R. ; and of Fahrenheit F., or Fahr. There- 
fore we may say that 0°C.=:0°R. = 32°F., 
and 100°C.=r80°R. = 180°F. ; and keeping 
these proportions in mind, it is quite easy 
to translate the reading of one scale into the 
other. 

The figure annexed shows us at a glance 
the several scales compared. The one on 
the right, marked De Lisle, was the contri- 
vance of a French astronomer, who proposed 
to call boiling water zero, and read down- 
wards, by 150°, to the freezing point. It 
is not used. We shall use only Fahren- 
heit's scale, which is so well understood in 
this country ; and a single example will 
show how we may convert the degrees of 
Centigrade or Reaumur into those of Fah- 
renheit. 100°C. = 80°R.ri:.180°F.isthesame 
as 5C.=r:4R. = 9F. Fahrenheit's scale (180°) 
is to that of Reaumur (100°) as 9 is to 5. 
To reduce Centigrade to Fahr., we can mul- 
tiply by 9 and divide by 5, and add 32° to the 
quotient, and vice versa. Suppose we wish 



90- 



QO 



50 



0-:E 



What was Fahrenheit's zero? How many degrees had he above zero 
to the boiling of water ? Give on the black-board an example of the con- 
version of the Centigrade scale to Fahrenheit, and the reverse. The 
same of Reaumur, and the reverse. 



* The word zero is from the Italian, and signifies ^ nothing,^ and was 
applied to the thermometer in allusion to the supposed absence of all heat. 



EXPANSION. 



61 



to know'what 70°C. is on Fahrenheit's scale, we have the 
proportion 5 : 9 : : 70° : 126°. If we add 32°, which is the 
difference between zero of F. and C, we have 126° + 32° 
= 158°, which is the thing required, for 70°C.=:158°F. In 
stating thermometrical degrees, the sign + is used for points 
above zero, and -— for those below. 

§ 79. The Self 'Registering Thermometer (often called, 
also, Six's thermometer) is a form of the instrument contri- 




1 1 1 1 1 ;^M 1 1 1 



ved for the purpose of ascertaining the extremes of varia- 
tions which may occur, as, for instance, during the night, or 
in sounding to great depths in the sea, or measuring the tem- 
perature of an artesian boring. It consists of two horizon- 
tal thermometers attached to one frame, as in the figure ; h, 
is a mercurial thermometer, and measures the maximum 
temperature, by pushing forward, with the expansion of the 
column, a short piece of steel wire, of such size as to move 
easily in the bore of the tube ; it is left by the mercury at 
the remotest point reached by the expansion ; «, is a spirit- 
of-wine thermometer, and measures the minimum temper- 
ature. It contains a short cylinder of porcelain, shown in 
the figure, which retires with the alcohol on the contraction of 
the column of fluid, but does not advance on its expansion. 
To use the instrument, it is necessary, before every observa- 
tion, to incline it, and with a slight jar, bring the cylinder 
of porcelain in a to the surface of the fluid. 

\ 80. The Differential Thermometer is a form of air-th|r- 
mometer, (§ 75,) with two bulbs on one tube, bent twice at 
right angles, and supported as shown in the figure ; a little 
sulphuric acid, water, or other fluid, partly fills the stem only, 
(shown by the cross-lines in the figure.) When the bulbs of 
this instrument are heated or cooled alike, no change is seen 



§ 79. What is the self-registering thermometer? Explain its construc- 
tion and use. § 80. What is the differential thermometer ? How is it 
used? 

6 



62 



HEAT. 




in the position of the column, but the instant any inequality 
of temperature exists between them, 
as from bringing the hand near one of 
them, the column of fluid moves rapidly 
over the scale. A modification of this 
instrument, of great delicacy, was con- 
trived by Dr. Howard of Baltimore, in 
which ether was used, the bulbs being 
vacuous. It is called a differential ther- 
mometer, because it notes only differ- 
ences of temperature, and not actual 
temperature. 

§ 8] . Pyrometers. — All common thermometers are limited 
to comparatively low temperatures. Mercury boils at about 
600°, above which we can judge of temperatures only by 
the expansion of solids. We have thermometers made with 
gases or vapors, and with fluids, and pyrometers made with 
solids. 

A Pyrometer"^ is an instrument for measuring high temper- 
atures. The only instrument of this sort which we need 

mention, (as it is the only one of 
any accuracy,) is DanieWs Re- 
I gister Pyrometer, It consists 
merely of a hollow case of black 
lead, (plumbago,) into which is 
dropped a bar of metal, (plati- 
num is preferable,) secured to its 
place by a strap of platinum and 
a wedge of porcelain. The 
whole is then heated, as for in- 
stance, by placing it in a pot of 
molten silver, whose temperature 
we wish to ascertain. The met- 
al bar expands much more than 
the case of black lead, and being confined from moving in 
any but an upward direction, it drives forward the arm of a 

§ 81. What is a pyrometer, and its use? What one is described, and 
its general construction ? 

* From the Greek, pur, fire, and metro, I measure. A very conven- 
ient form of pyrometer for illustration, is made by all instrument-makers, 
which shows the expansion of a metallic bar, heated by a spirit-lamp, 
moving an index like a clock-pointer. 




EXPANSION. 63 

lever, as shown in the figure, over a graduated arc, on which 
we read the degrees of Fahrenheit's scale ; (this graduation 
has been determined beforehand with great care.) This 
instrument gives very accurate results ; by it the meking 
point of cast iron has been found to be 2786° F., and of 
silver, 1860° F. The highest heat of a good wind-furnace, 
is 3300° F. 

Having, to a sufficient extent, become acquainted with in- 
struments for measuring temperature, and with the principles 
of their construction, we can now proceed intelligently with 
our main subject. 

§ 82. Expansion of Solids and Liquids. — (1.) Different 
solids expand differently with equal increase of temperature. 
(2.) The same solid expands equally for every equal addi- 
tion of heat below 212°. Between the freezing and boil- 
ing of water, 350 cubic inches of lead become 351 ; 800 of 
iron become 801 ; and 1000 of glass become 1001. Each 
solid, in fact, has a rate of expansion peculiar to itself. The 
same is true of liquids. 1000 parts of water between 32° 
and 212°, expand to 1046 parts; and 1000 parts of quicksilver 
become 1080 parts. The expansions are gradual both in 
solids and liquids, and on withdrawing the heat, they return 
with equal regularity to their former dimensions. Above 
212° the expansion of both solids and liquids becomes irreg- 
ular and increases. 

I 83. The unequal expansion of solids is well shown by 
joining firmly, by rivets, two bars, one»of iron and one of 

brass, as in the figure. If £ ^_^___L r 7 : .■ - -7—r-~r~^~- — -^ a 

they be heated, the brass ^^^~'''~~"" --^— . - u , \^ 

expanding most, will cause 

the compound bar to bend, r^^^^^^^^^^^^^^^^^-^ 
as shown in the lower fig- ^^*^^s^ 

ure. If they be cooled by ice, the brass contracting most, 
will bend the united metals in an opposite direction. 

§ 84. The Compensation Pendulum gives a beautiful ap- 
plication of the law of unequal expansion in regulating the 
rate of time-pieces. The length of the pendulum, or rather 



Name some of the results obtained by it. § 82. (1.) How do solids ex- 
pand? (2.) How with equal increments of heat? Name some exam- 
ples. Also some of liquids. Is the effect sudden ? § 83. How is the 
unequal expansion of solids well shosvn ? 



64 



HEAT. 



the uniform position of its centre of gravity, is altered by 
variations of temperature, and of course the rate of the 





clock is disturbed, A perfect " compensation^^ for this error 
is obtained by the use of a compound pendulum of brass 
and iron, or other two metals, arranged as is shown in fig- 
ure (2, in such a manner that the expansion of one metal 
downwards will exactly counteract that of the other metal 
upwards ; thus preserving the ball of the pendulum at the 
same distance from the point of suspension. The shaded 
bars represent the iron, and the light ones, the brass. The 
same object is accomplished by using mercury, as shown in 
figure Z>, contained in a glass or steel vessel at the end of 
the pendulum-rod. The expansion which lengthens the rod 
also increases the volume of the mercury ; this increase of 
bulk in the mercury raises the centre of gravity to an 
exactly compensating amount, and the clock remains un- 
altered in rate. Watches and chronometers are regulated 
by a like beautiful contrivance. The balance-wheel c, 
on whose uniform motion the regularity of the watch or 
chronometer depends, is liable to a change of dimensions 
from heat or cold. If made smaller, it will move faster, and if 
larger, slower. To avoid this error, the outside of the wheel 

§ 84. Give a practical use of this in the clock, (a,) (b.) Also in the 
watch, (c.) 



EXPANSION. 65 

is made of brass, the inside of steel, and cut at two opposite 
points ; one end of each part is screwed to the arm, and 
the loose ends of the rim, being secured by a screw, are 
drawn in or thrown out by the changes of temperature, in 
precise proportion to the amount of change ; thus perfectly 
adapting the revolution of the wheel to the force of the 
spring. The principle of this wheel will be seen in the 
compound bars, (^ 83.) * 

§ 85. Practical application of the laws of expansion in 
solids, is frequently made with great advantage in the arts. 
The rivets which hold together the plates of iron in steam- 
boilers are put in and secured while red-hot, and on cooling, 
draw together the opposite edges of the plates with great 
power. The wheel-wright secures the. parts of a carriage- 
wheel by a red-hot tire, or belt of iron, w^hich being quickly 
quenched, before it chars the wood, binds the whole fab- 
ric together with wonderful firmness. The walls of the 
Conservatory of Arts at Paris were safely drawn into a 
vertical position, after they had bulged badly, by the alter- 
nate contraction and expansion of large rods of iron, passed 
across it, and so secured by screw-nuts, and heated by argand 
lamps, as to draw the walls inward. Towers of churches 
and of other buildings have been thrown down or otherwise 
injured, by the expansion of large iron rods (anchors) built 
into the masonry, with the design of strengthening them. 
The mechanical arts are, in fact, full of beautiful applica- 
tions of the principles of expansion. 

§ 86. Unequal expansion of Water. — The general law 
of expansion for nearly all solids and fluids, especially 
within the limits of freezing and boiling points of water, is, 
that each solid or fluid expands or contracts an equal amount 
for every like increase and reduction of temperature, each 
body having its own rate of alteration. {^ 82. ) There are, 
however, some exceptions to this law, of which water offers 
a remarkable example ; the comfort and even habitability of 
our globe are in a great degree dependent on this exception 
to the ordinary laws of nature. We will briefly explain it 
and the effects resulting from it. 

If we All a large thermometer-tube or bulbed glass (like 
the one figured in ^ 74, a) with water, and place it in a 

§ 85. Name some other practical applications of the same principle in 
the arts. § 86. Explain the unequal expansion water. 



66 HEAT. 

cold situation, where we can observe by the thermometer* 
the fall of the temperature, we shall see the column descend 
regularly with the temperature, until it reaches 40^, (or 
more accurately 39° -5 F.,) when the contrary effect will 
take place ; the water then begins suddenly to rise, by a 
regular expansion, until the temperature falls to 32°, when 
so sudden an expansion takes place, as to throw the water 
in a jet from the open oitfice of the tube, and the ball 
is frequently broken from the solidification of the water. If, 
on the other hand, we heat water in such an apparatus, 
commencing with it at 32°, we shall find that, until the tem- 
perature rises to 40°, the fluid, in place of expanding as we 
might expect, and as other fluids would do, will actually 
contract. Water has, therefore, its greatest density at 
39°*5, and its density is the same for equal temperatures 
above and below this point ; thus we shall find it having a 
similar density at 34° and 45°, and this is true until it reaches 
the point of solidification at 32°. 

§ 87. Beneficial Results. — Let us now observe what use- 
ful end this curious irregularity in the expansion of water 
subserves. When winter approaches, the lakes and rivers 
by the contact of the cold air, begin to lose their heat on the 
surface ; the colder water, being more dense, falls to the bot- 
tom, its place being supplied by warmer water rising from 
below. A system of circulation is thus set in motion, and 
its tendency, if the mass of water is not too large, is to reduce 
the whole, gradually, to the same temperature throughout. 
When, however, the water has cooled to 40°, this circula- 
tion is suddenly stopped by the operation of the law just ex- 
plained : below this point the water no longer contracts by 
cooling, and of course does not sink, but on the contrary ex- 
panding^ as before explained, it becomes relatively lighter, and 
remains on the surface ; the temperature of this layer or up- 
per stratum gradually falls, until the freezing point is reached 
and a fihn of ice is formed. But as ice is a very bad con- 
ductor, the heat now escapes with extreme slowness ; all 
currents tending to convey away the cooler partsof the water 

At what temperature is water most dense? § 87. Explain the use of 
the irregular expansion of water, and its operation in nature. 

* A freezing mixture of salt and ice surrounding It will answer the 
purpose very well. 



COMMUNICATION OF HEAT. 67 

are arrested, and the thickness of the ice can increase only by 
the slow conduction through the film already formed : the 
consequence is, that our most severe winters fail to make 
ice of any considerable thickness, two feet being in these lat- 
itudes almost the greatest limit ever known. Other causes, 
also, which we shall presently explain, cooperate at all 
times to render the freezing of water a very slow process. 
If this irregularity did not exist, there is every reason to 
believe that the entire waters of the globe^ would freeze 
solid : when any portion reached the point of congelation, all 
would become solid at once, like a mass of molten metal 
cooled in a crucible. We cannot fail to be impressed by the 
wisdom of that power, which not only frames great general 
laws for the government of matter, but also makes excep- 
tions to them, when the welfare of His creatures requires 
them. 

§ 88. The expansion of all gases and vapors is the same 
for an equal degree of heat, and equal increments of heat 
produce equal amounts of expansion. This rate of expan- 
sion is not altered by any change in the compression or 
elastic force of the gas, and amounts to -j^th part of the 
volume of the gas at 0° for each degree of Fahrenheit's 
scale. 

When gases are near the point of compression at which 
they become liquid, this law is modified. 

The expansion of gases by heat, is one cause of winds 
and atmospherijc currents. The trade-winds and other reg- 
ular winds so well known to mariners, are the joint result of 
the motion of the earth on its axis, and the rise of heated 
air from the equatorial regions of the globe. A discuss- 
ion of these very interesting topics would, however, lead us 
away from our present object. 

2. Communication of Heat. — Equilibrium of Temperature. 

§ 89. Equilibrium of Temperature. — A heated body, like 
a red-hot cannon-ball, cools when removed from the source 
of heat ; (1) by communicating its heat to the substances 

What might happen but for this exception ? 

* Sea-water above 32^ is not subject to the cxcepiion, but it is below 

280. 



68 HEAT. 

supporting it, (conduction ;) (2) by the contact of the atmos- 
phere conveying it away, (convection ;) and (3) by direct 
radiation, or a transmission of rays of heat in all directions 
through the surrounding air, as light (^ 52) is transmitted. 
All these causes act to withdraw the excess of heat from 
the heated body, which thus divides itself equally among 
them all, according to their several powers of receiving it, 
until, a perfect equilibrium of temperature being produced, the 
hot body has become cool, and the surrounding bodies have 
gained heat. 

In liquids or gases, this uniform diffusion or distribution 
of temperature takes place rapidly, because of the mobility 
of their particles ; but in solids, much more slowly. Its dif- 
fusion has no connection with the conducting power of the 
fluids, however, which are among the worst of conductors. 

§ 90. Conduction of iiTea^. — Each solid has its own pecu- 
liar power of conducting heat, but in all it is a progressive 
operation, the heat seeming to travel from particle to parti- 
cle wath greater or less rapidity, according to the conducting 
power of the solid. If we hold a pipe-stem or glass rod 
in the flame of a spirit-lamp or candle, we can heat it to 
redness within an inch of our fingers with no inconvenience ; 
but a wire of silver or copper would burn us in a very short 
time when at the distance of many inches from the flame. 
I -■ This is owing to a 

^ ^ ^ ^ ^ ^ T"^ difl-erence inherent in 

W these solids, which we 
call conducting power. The progress of conducted heat in 
a solid is easily shown, as in the annexed figure, representing 
a rod of metal, to which are stuck by wax several marbles, at 
equal distances ; one end is held over a lamp, and the mar- 
bles drop ofl", one by one, as the heat melts the wax ; that 
nearest the lamp falling first, and so on. If the rod is of cop- 
per, they all drop very soon ; but if a rod of 
lead or platinum is used, the heat is conveyed 
much more slowly. Little cones of various 
metals, and other substances, may be tipped 



§ 89. What is equilibrium of temperature? Explain how a hot body 
may cool. (1.) (2.) (3.) How does the diffusion of heat take place in 
gases and hquids ? How in solids? §90. Explain conduction in solids. 
What experiments are named in illustration of it? 





COMMUNICATION OF HEAT. 69 

with wax or bits of phosphorus,* as shown in figure 5, and 
placed on a hot surface. The wax will melt, or the phos- 
phorus inflame, at different times, according to the conduct- 
ing power of the various solids. Accurate experiments have 
been made, which have enabled us to arrange most solids in 
a table expressing their conducting powers. The metals as 
a class are good conductors, while wood, charcoal, fire-clay, 
and such like bodies, are bad ones. Thus gold is the best con- 
ductor, and may be represented by the number 1000 ; then 
marble will be 23*5, porcelain 12, and fire-clay 11. Metals 
compared with each other are very different in conducting 
power. Thus — 



Gold, 


1000- 


Iron, 


375- 


Silver, 


973- 


Zinc, 


363- 


Copper, 


898- 


Tin, 


304- 


Platinum, 


381- 


Lead, 


180- 



§ 91. The sense of touch gives us a good idea of the dif- 
ferent conducting power of various solids. All the articles 
in an apartment have nearly the same temperature ; but 
if w^e lay our hand on a wooden table, the sensation is very 
different from that we feel on touching the marble mantle, or 
the metal door-knob. The carpet will give us still a different 
sensation. The marbley^eZ^ cold, because it rapidly conducts 
away the heat from the hand, while the carpet, being a very 
bad conductor, retains and accumulates the heat, and thus feels 
warm. Clothing is not itself warm, but being a bad conduc- 
tor retains the h-eat of the body. A film of confined air, is 
one of the worst conductors ; loose clothes are, therefore, 
warmer than those which fit closely. For the same reason, 
porous bodies, like charcoal, are bad conductors. From this 
cause, a wooden handle enables us to manage hot bodies 
with ease. 

§ 92. The conducting power of fluids is very small. This 
is contrary to the general impression of people, who think, 
from the ease with which a tea-kettle boils, that liquids 



How are the different classes of bodies as conductors? Name some 
examples. Give some examples from the table. §91. Explain the re- 
lation of our sense of touch to the conducting power of bodies. 



* If phosphorus is used, some screen must be employed to cut off the 
radiant heat, which will otherwise inflame it prematurely. 



70 



HEAT. 



conduct heat with facility. There is, however, more phi- 
losophy in the boiling of a kettle than 
is generally known. A simple and in- 
structive experiment will prove to us 
that the conducting power of fluids is 
very low. A glass, like that in the 
figure, is filled nearly to the brim with 
water. A thermometer-tube, with a 
large hall, is so arranged in it, that the 
ball is just covered, and no more, with 
the water ; the stem passes out at the 
bottom through a tight cork, and has a 
little colored fluid, L, in it, which will 
of course move with any change of 
bulk in the air contained in the ball. 

Thus arranged, a pointer, I, marks 
exactly the position of one of the 
drops of inclosed fluid, and a little 
ether is poured on the surface of the 
water, and set on fire. The flame 
mounts and is intensely hot : it rests on 
the surface of the water, and as it seems, 
must heat it. The column of fluid at 
I is, however, unmoved, which would 
not be the case, if any sensible quan- 
tity of heat had been imparted to the 
water. The warmth of the hand touch- 
ing the ball, will at once move the 
fluid at I. By heating a vessel of water 
on the top, then, we should never succeed in creating any 
thing more than a superficial boiling ; at the depth of a few 
inches, the water would remain cold. 

^ 93. The conducting power of gases is also very small. 
Heat travels with extreme slowness through a confined por- 
tion of air. (§ 91 .) This is a very different thing from the con- 
vection of heat in gases, which we will presently explain. 
Double windows and doors, and furring^ so called, of plas- 
tered walls, are excellent illustrations of the slow conduction 
of heat through confined air. We have no proof that heat 
can he conducted in any degree by gases and vapors. As 




§ 92. How is the conducting power of fluids ? Give an experimental 
illustration. ^ 93. How is it in gases ? Give illustrations. 



COMMUNICATION OF HEAT. 



71 



an illustration of the relative conducting power of solids, 
fluids, and gases: if we touch a rod of metal heated to 120^, 
we shall be severely burned; water at 150° will not scald 
ns if we keep the hand still, and the heat is gradually 
raised ; while air at 300° has been often endured without in- 
jury. 'The oven-girls of Germany, clad in thick socks of 
woolen, to protect the feet, enter ovens without inconven- 
ience, where all kinds of culinary operations are going on, 
at a temperature above 300° ; although the touch of any me- 
tallic article while there would severely burn them. 

§ 94. Convection of Heat.— Fluids and gases are heated 
by what is termed Convection. Heat applied to a vessel 
from beneath, containing water, heats 
the layer or film of particles in 
contact with the vessel. These ex- 
pand with the heat, and consequent- 
ly, being lighter, rise, and colder 
particles supply their place, which 
also rise in turn, and so the whole 
contents of the vessel come into con- 
tact successively with the source of 
heat, and convey it away. This is 
well illustrated in the annexed figure, 
which shows how water acts in a 
vessel of glass, when heated at a 
point beneath, by a spirit-lamp. 
Each particle in turn comes under 
the influence of heat, because of the 
perfect mobility of the fluid, and the 
heat is thus conveyed to, and distrib- 
uted throughout, the whole mass. 
A series of such currents exist in 
every vessel in which water is boiled, and they are ren- 
dered more evident in water, by throwing into it a few grains 
of some solid, (like amber,) so nearly of the same gravity of 
water, that it will rise and fall with the currents. A per- 
petual circulation is thus established in fluids, which serves 
to keep up the equilibrium of temperature. 

What comparative trial in solids, fluids, and gas, is named? What is 
said of the oven-girls in Germany ? § 94. How are fluids and gases 
heated? Explain what is meant by convection of heat. Give an ac- 
count of the experiment. 




72 HEAT. 

§ 95. In the air, and in all gases and vapors, the same thing 
happens. The earth is heated by the sun's rays, and the 
film of air resting on the heated surface rises, or tends to 
rise, and is replaced by colder air. The rarified air may be 
easily seen on a hot day, rising from the surface of the earth, 
being made visible by its higher refractive power. Hence 
arise many aerial currents and winds. The currents of the 
ocean are also influenced by the same cause. 

§ 96. Convection and conduction of heat will, therefore, be 
carefully distinguished from each other by the learner. Heat 
is, so to speak, transported rapidly in fluids by convection, 
while by conduction it travels slowly and progressively from 
particle to particle, within the limits of the body subject to it. 

§ 97. Radiant Heat. — We have sometimes spoken of the 
sun's rays as composed both of light and heat : these rays 
of heat proceed from all hot bodies, at all temperatures, for 
the slightest disturbance of the equilibrium of temperature 
will occasion their emission. Radiant heat is subject in all 
respects to the same laws, and possesses the same habitudes 
as radiant light. It can pass through but few substances ; 
it is subject to reflection, absorption, refraction, and polari- 
zation. Radiation of heat takes place in a vacuum much 
more rapidly than in air, and is, therefore, quite independent 
of any conducting medium. 

§ 98. Reflection of heat is shown by the concave parabolic 
mirror. All rays of heat or light falling on this form of metal- 
lic mirror are collected at F, the focus, and 
a hot body placed in the focus will have its 
rays sent forth in parallel straight lines, as 
shown in the figure. A second and simi- 
lar mirror may be so placed as to receive 
and collect in a focus all the rays proceed- 
ing from any body in the focus of the other, 
where they will become evident by their 
efl*ect on the thermometer. If the hot 
body be a red-hot cannon-ball, and the mir- 
rors carefully adjusted, so as to be exactly 

§ 59. Explain the origin of aerial and oceanic currents. § 96. Con- 
trast the effects of convection and conduction. § 97. What is radiant 
heat? From what bodies does it flow, and why? What is said of its 
properties ? § 98. Explain the reflection of heat, and the metallic mir- 
rors. 




COMMUNICATION OF HEAT. 



73 





by the dull sur- 
sensibly hotter, 



opposite each other in the same line, the accumulation of 
heat in the focus of the second mirror is such, as easily to 
inflame gunpowder or dry tinder, even at twenty feet dis- 
tance. This arrangement is shown in the annexed figure, 
and the experiment is 
a most striking and 
satisfactory one. It 
is quite essential that 
the mirrors should be 
highly polished ; oth- 
erwise the heat, in 
place of being reflect- 
ed to the second mirror, will be ahsorhed 
face. A bright mirror will not become 
from the near approach of the hot body, nearly the whole 
heat being reflected ; but a black mirror will grow rapidly 
hot, and will then emit heat itself, by what is called second- 
ary radiation, 

§ 99. The formation of dew is owing to radiation, cooling the 
surface of the earth so rapidly, that the moisture of the air, 
which is always abundant in summer, is condensed upon it, 
as we see it on the outside of a tumbler of iced-water in a 
hot day. Radiation takes place more rapidly from the sur- 
face of grass and vegetation, than from dry stones or dusty 
roads : for this reason, plants receive abundant dew, while 
the barren sand has none. 

§ 100. Radiation of cold was formerly supposed to occur, 
because a mass of ice placed in the focus of one mirror, 
caused the thermometer in the other to fall. The true expla- 
nation of this is, that the thermometer, in this case, is the 
hot body, and parts with heat to melt the ice, and thus re- 
store the equilibrium of temperature. Cold is merely the 
absence of heat, and is a negative, and not a positive quality. 
^101. Absorption of Heat. — All black and dull surfaces 
absorb heat very rapidly when exposed to its action, and 
part with it again by secondary radiation. The sun shin- 
ing on a person dressed in black, is felt with much more 
power than if he were dressed in white. The former color 
rapidly absorbs heat, while from the latter a considerable 



What experiment is shown by the mirrors ? What if they are dull 
or black? §99. Explain dew. §100. Explain the supposed radiation 
of cold. § 101. How does color affect absorption? 

7 



74 HEAT. 

part of it is reflected. Prof. A. D. Bache has shown, how- 
ever, that the color of bodies has nothing to do with their 
radiating powers, and that, therefore, one colored cloth is as 
warm in winter as another, as regards the emission of heat. 
§ 102. The nature of the surface of bodies has the great- 
est effect on their several powers of radiation. Hot water 
in a bright tin canister, or a polished silver tea-pot, will re- 
main hot very much longer than in a vessel with dull or 
roughened surfaces. A coating of lamp-black on the sur- 
face of a tin canister, placed in the focus of the mirror, will 
radiate five times more heat from boiling water than clean 
lead, and eight times more than bright tin, as proved by the 
differential thermometer. Bright metals have tbe lowest ra- 
diating power, and hence are selected to preserve heat in 
those substances which we wish to keep hot. For the same 
reason, they are the worst vessels in which to heat a fluid. 
The effort to boil water in a bright copper tea-kettle, would be 
very tedious ; as soon, however, as the surface becomes sooty 
from the fire, the heat passes in rapidly. A dull c^^-^-iron 
stove radiates much more heat than a polished sheet-iron 
one — the openness of the pores and great number of points 
of the cast iron materially aid its radiating power. 

3. Transmission of Heat through Bodies. 

^ 103. The rays of heat from the sun, like the rays of 
light from the same luminary, pass through transparent sub- 
stances with little change or loss. Radiant heat, however, 
from all terrestrial sources, whether luminous or not, is in a 
great measure arrested by many transparent substances.* If 
the sun's rays be concentrated by a metallic mirror, the 
heat accompanying them is so intense at the focus as to 
fuse copper and silver with ease. A pane of colorless win- 
dow-glass interposed between the mirror and the focus, will 
not stop any notable part of the heat. If the same mirror 

Does it affect radiation? § 102. What chiefly affects radiating power? 
Give illustrations. § 103. Give the distinction between rays of heat from 
the sun, and those from most terrestrial substances. How are the latter 
affected by glass and other transparent substances? 

* The compound, or oxy hydrogen blow-pipe, and the galvanic focus, 
form exceptions, the light from these sources having the properties of 
the solar rays. 



TRANSMISSION OF HEAT THROUGH BODIES. 75 

be presented to any other source of heat, however, (as the 
red-hot ball, ^ 98,) the glass plate will stop nearly all the 
heat, although the light is undiminished. We thus dis- 
tinguish two sorts of calorific rays, which are sometimes 
called (1) Solar Heat, and (2) Culinary Heat^ and we dis- 
cover that substances transparent to light are not, so to speak, 
transparent to heat. This property is distinguished from 
transparency by the term Diathermancy J^ Bodies allowing 
the passage of the heat are said to be diathermous, while 
those allowing the passage of light are said to be diaphanous.^ 
Bodies which completely arrest the passage of radiant heat 
are said to be athermous.\ 

Bodies which are highly transparent or diaphanous, are 
often completely athermous, so that the transparency of a 
body is not connected with its diathermancy. 

Thus glass of various sorts arrests from 47 per cent, to 
67 per cent, of the rays of heat, while common alum in 
perfectly clear masses allows the passage of only 12 rays in 
100. On the other hand, rock-salt stops only 8 rays in 100, 
92 passing freely through. These facts are easily shown, 
when no other means are at hand, by placing a tablet of 
rock-salt and one of glass in a situation to be exposed to 
the heat of a fire. The glass will soon grow so hot as to 
burn the fingers, from the quantity of heat arrested by it, 
while the salt will hardly be aflected. A large air-ther- 
mometer, or a delicate differential one, with one ball black- 
ened, will also answer to make many of these changes 
of temperature evident, in the absence of the more delicate 
means explained in the next section. 

§ 104. Melloni^s Apparatus. — Nearly all the knowledge we 
possess on this interesting branch of science, we owe to the 
labors of a distinguished Italian philosopher, still living, M. 
Melloni, who has invented a most beautiful apparatus, by 
which all these observations and discoveries have been made. 
Its general arrangement is represented in the annexed fig- 

What is Diathermancy? What is meant by diaphanous? What by 
athermous? Are these properties united generally ? Give instances. 

* From the Greek, dia^ through, and thermos, heat, in allusion to the 
passage of heat through substances. 

t From the Greek, dia^ through, and phiano, to shine. 
X From the Greek, a, not, and thermos, heat. 



76 



HEAT. 



ure. The degree of heat is measured in this instrument, not 
by a thermometer, (which would be altogether too rude an 

h a 




indicator of such minute changes of temperature as are 
here shown,) but by what is called a thermo-multiplier, or 
multiplier of heat. This is an arrangement of little bars of 
the two metals, antimony and bismuth, about fifty of which 
are soldered together by their alternate ends, the whole 
being with its case not more than 2i inches long, by i to J 
of an inch in diameter. The least difference of heat be- 
tween the opposite ends of this little battery, will produce 
an electrical current capable of influencing a magnetic 
needle, in an instrument called a galvanometer. The needle 
of the galvanometer will move in exact accordance to the 
intensity of the heat. This is so delicate an instrument that 
the radiant heat of the hand held near the battery, will cause 
the needle to move some 10° over its graduated circle. In 
the figure, a is the source of heat, (an oil-lamp in this case,) b, 
a screen having a hole to admit the passage of a bundle of 
rays ; c is the substance on which the heat is to fall ; d the 
thermo-multiplier, or battery, which is to receive the rays 
after they have passed the substance c. Two wires con- 
nect the opposite members of this battery with the galvan- 
ometer e, which, for steadiness, is placed on a bracket at- 
tached to the wall. Thus arranged, and with various 
delicate aids which vv^e cannot now explain, a vast number 
of most instructive experiments have been made on radiant 
heat, from various sources, and its eflect ascertained on vari- 
ous substances. Four different sources of heat were em- 
ployed : (1) the naked flame of an oil-lamp ; (2) a coil of plati- 
num wire heated to redness by an alcohol-lamp ; (3) a surface 
of blackened copper heated to 734°, and (4,) the same heated to 



§ 104. Explain Melloni's apparatus from the figure, 
heat were used ? 



What sources of 



TRANSMISSION OF HEAT THROUGH BODIES. 



77 



212° by boiling water. The first two of these are luminous 
sources of heat, the last two not so. 

The following table will show a few of the principal re- 
sults. 



Names of interposed substances, common thick- 
ness, 0-102. 


Transmission of 100 
rays of heat from 


S 

o 








Rock-salt, transparent and colorless, 

Iceland-spar, 

Plate -glass, 

Rock-crystal, 

Rock-crystal, brown, .... 
Alum, transparent, . . . . . 

Sugar-candy, 

Ice, pure and transparent, .... 


92 

39 

39 

38 

37 

9 

8 

6 


92 

28 

24 

28 

28 

2 






92 
6 
6 
6 
6 





92 










Thus it appears that rock-salt is the only substance which 
permits an equal amount of heat from all sources to pass. 
In other cases the number of rays passing seem proportioned 
to the intensity of the source. M. Melloni has called rock- 
salt the glass of heat, as it permits heat to pass with the 
same ease that glass does light. It is supposed that the 
difference found by experiment in the diathermancy of bodies, 
is owing to a peculiar relation which the various rays of 
heat sustain to these bodies, exactly analogous to that differ- 
ence in the rays of light which we call color. Thus all 
other bodies, except salt, act on heat as colored glasses act 
on light, entirely absorbing some of the colors, and allowing 
others to pass. Opake bodies, like wood and metals, en- 
tirely prevent the transmission of heat ; but dark-colored 
quartz is seen, by the table, to differ only 1 from white quartz, 
and even perfectly black glass does not entirely stop all heat. 

§ 105. By cutting rock-salt into prisms and lenses, Prof. 
Forbes has shown that the heat from radiant bodies may be 
reflected, refracted, and concentrated, like light, and that 
doubly refracting minerals, like Iceland-spar, will polarize it. 
All these interesting results, however, we must pass without 
further notice. 

Give some illustrations of the results from the table. What has rock- 
salt been called, and why ? To what are the difterent powers of bodies 
in this respect supposed to be owing ? § 105. How have the other attri- 
butes of light been discovered in radiant heat? 



78 HEAT. 

4. Specific Heat. — Capacity of Bodies for Heat, 

§ 106. Specific heat is that amount of heat required to raise 
any body through a given number of degrees of temperature, 
as, e. g., 10°. It is a remarkable fact, and one of great impor- 
tance, that the same quantity of heat cannot raise different 
bodies through an equal number of degrees of temperature. 
If equal measures (say a pint) of mercury and water be 
equally exposed before the same source of heat, we shall 
find that the mercury will attain its highest temperature about 
twice as soon as the water ; and on removal from the fire, it 
will cool in half the time. If a pint measure of water at 150° 
be mixed quickly with an equal measure of the same fluid at 
50°, the two measures of fluid will have the temperature of 1 00°, 
or the arithmetical mean of the two temperatures before mix- 
ture. If, however, we take one measure of water at 1 50°, and 
an equal measure of mercury at 50°, and rapidly mix them, 
we shall find that they will have the temperature of 118°. 
The mercury has gained 68°, and the water lost only 32°, or 
about half as much. Hence we infer that the same quan- 
tity of heat can raise the temperature of mercury through 
twice as many degrees as that of water. We thus prove, by 
actual trial, that each body (solid, fluid, or gas) has its own 
relation to the amount of heat required to raise it a given 
number of degrees of heat, and this amount being peculiar 
to each body, is called its specific heat. As water is adopt- 
ed as the standard of comparison for specific heats, the spe- 
cific heat of mercury will be to water as 68 to 32, or nearly 
0-47. It is more convenient to compare bodies by weight 
than by measure ; and hence if we divide the specific heat 
by measure (0'47) by the specific gravity of mercury, (13*5,) 
we obtain the number, 0*035, its specific heat, by a compar- 
ison of weights. The process just described for determin- 
ing specific heat, is called the method of mixtures. 

§ 107. The method of mixtures can be used to obtain the 
specific heat of solids as well as fluids. Thus a bar of cop- 
per of a pound weight may be heated to a temperature of 
400°, and then put into a pound of water at 50°; when the 



§ 106. What is specific heat? lUustrate this in the case of mercury 
and water. Give the specific heat of mercury by measure and weight. 
What is this method called ? § 107. Is it used for solids, and how ? Give 
some examples from table. 



CHANGES PRODUCED BY HEAT. 



79 



equilibrium is restored, both will have the temperature of 
72°. The copper has lost 228°, and the v/ater has gained 
22°. The specific heats being then as 228 : 22, that of the 
copper is found to be -^rf~^z=zQ'096. Other methods have 
been used to determine specific heats, but it is foreign to 
our present purpose to describe them. The following table 
will show the specific heats of a number of common sub- 
stances : 



Water, 


1-000 


Copper, 


0-095 


Ether, 


0-520 


Lead, 


0-031 


Alcohol, 


0-660 


Gold, 


0032 


Sulphuric Acid 


, 0-333 


Antimony, 


0-051 


Mercury, 


0-033 


Tin, 


0-056 


Silver, 


0-057 


Phosphorus, 


0118 


Zinc, 


0-095 


Glass, 


0-197 


Iron, 


0114 


Lime, 


0-205 



The property of specific heat is found to be most inti- 
mately connected with the chemical character of the sub- 
stance, and many curious and important inferences have been 
made from the study of these relations. We shall have oc- 
casion to refer to this subject again, in the chapter on Chem- 
ical Philosophy. 

5. Changes produced hy Heat on the state of Bodies. 

§ 108. Liquefaction. — The change of a solid to a fluid is 
called liquefaction, and is always attended by a remarkable 
absorption of heat. Water is a substance familiarly known 
under all three states of solid, fluid and gaseous ; and the 
melting of ice will furnish us a good instance of the phe- 
nomena which take place in the process of liquefaction. 
We have already seen that two equal measures of water at 
different temperatures would, when mingled, have a temper- 
ature which was the mean of their previous temperatures, 
(§ 106.) If, however, we take a pound of ice [solid water) 
at 32°, and a pound of water at 212°, we shall find, when 
the ice is melted, that the two pounds of water have the 
temperature of only 52° ; the ice gains only 20°, while the 
water has lost 160°. There are 140° of heat t-fen lost in 
producing this change. We can take another mode of trial. 
Let us expose a pound of ice at 32°, and another pound of 



^ 108. What is liquefaction? 
to water. 



Explain and illustrate the change of ice 



80 HEAT. 

water at the same temperature, to a constant source of heat, 
in two vessels every way alike, and note the changes of tem- 
perature by the thermometer. When the ice is all melted, 
we shall find the water into which it is converted Las still 
only the temperature of 32°, while the other pound of water 
has risen from 32° to 172° ; here then again we see the loss of 
140° of heat used in converting the ice into water. We may 
also reverse the last experiment, and take equal weights of 
ice at 32° and water at 172°, and mix them ; the ice will 
soon be all melted, and the mixture will have the temper- 
ature of only 32° : so that, in whatever way we may make 
the trial, we constantly observe the loss of 140° of heat. 
This is called the heat of jiuidity^ it being necessary to the 
existence of the water in a fluid state, and it is also com- 
monly called latent heat, because it is lost, absorbed, or con- 
cealed, as it were, and no indication of it can be found by 
the thermometer. 

§ 109. Congelation. — If a vessel filled with water at 52° 
be placed in an atmosphere of 32°, it will rapidly cool down to 
32° by the loss of 20° of temperature. After this, it will, as 
may be seen by the thermometer, remain at 32°, until it is all 
converted to solid ice ; although w^e cannot doubt that it is 
all the while giving out a quantity of heat, which had before 
been insensible or latent. If the water had been ten minutes 
in cooling from 52° to 32°, (or in losing 20°,) then it would 
require one hour and ten minutes, or seven times as long, for 
it to become completely frozen. If, then, in equal times it 
lost equal degrees of heat, its latent heat will be 20° x 7 = 
140°, which is the same result as before. 

Thus it is by a wise order of Providence that the freezing 
and thawing of snow and ice are extremely slow and grad- 
ual processes. If water became solid at once on reaching 
32°, the water would be suddenly frozen to a great depth ; 
and if ice melted as quickly on reaching the same temper- 
ature, the most sudden and dreadful floods would accompany 
these events, and the common changes of the seasons would 
be calamitous to human life and comfort. 



What amount of heat is in all these eases unaccounted for? What is 
this lost heat called? What becomes of it? § 109. State the phenome- 
na observed in freezing. How do we then discover the same quantity of 
latent heat in water? What reflection is hence drawn in the order of 
Provideiiee ? 



LIQUEFACTION, 81 

§ 110. Freezing is a warming process. — Water may be 
cooled below its freezing point and still remain liquid, if its 
surface be covered with a thin film of oil, and if it is in a thin 
smooth vessel, free from any jar ; but the least disturbance will 
cause it, when in this situation, to become solid at once, and 
the temperature will immediately rise from 23°* or 24° to 32°. 
The freezing of a part has therefore given out heat enough to 
raise th« temperature of the whole from 24° to 32°, or through 
8°. In like manner, it is true that melting is a cooling pro- 
cess, although it seems paradoxical to say so. A solid cau 
melt (become liquid) only by absorbing heat from surround- 
ing bodies, which must, of course, become cooler. Hence 
the cooling influence of an iceberg, which is often felt for 
many leagues, or of a large body of snow on a distant moun- 
tain. 

^111. Freezing mixtures^ or the means used to produce 
artificial cold, owe their powers to the principles just ex- 
plained. Ice-cream is frozen by a mixture of snow or 
pounded ice with common salt. In this case the two solids 
are rapidly changed to fluids : the ice is melted by the 
salt, and the salt is dissolved by the water from the melting 
ice. Both these operations absorb (or render latent) a large 
quantity of heat. The surrounding bodies are called on to 
supply the heat required, and the cream, in a thin metallic 
vessel, loses heat so rapidly from this cause, as to be soon 
turned to ice. The thermometer will fall in this operation 
to 0° F. ; and this was the very experiment by which Fah- 
renheit so unwisely assumed that he had attained to a true 
zero of cold. 

Nitrate of ammonia dissolved in water at 46° will sink 
the temperature to zero, and the exterior of the vessel be- 
comes at once thickly covered with hoar-frost. Common 
saltpetre, (nitrate of potassa,) dissolved in water, lowers its 
temperature several degrees, and is therefore much used in 
the hot regions of Asia, where it abounds, for cooling wine. 
Mercury may be frozen by using a mixture of three parts of 
chloride of calcium, and two of dry snow ; this mixture will 
sink the temperature from +32° to — 50°. It should be di- 

§ 110. How is freezing a warming process? Illustrate this. Why is 
melting a cooling process? § ill. What are freezing mixtures? To 
what do they owe their power? Give some examples. 

* It may with care be cooled even lowex. 



82 HEAT. 

vided into two pretty abundant portions ; the first of which 
serves to cool down the mercury, and the second is used 
when the first is exhausted, and completes the work. 

But all other means of producing cold are insignificant, 
when compared to the power of solidified carbonic acid gas, 
in a vacuum, by means of which, Dr. Faraday has succeeded 
in obtaining a temperature of — 175^ below zero of Fahren- 
heit's thermometer. 

§ 112. The melting point of every substance is very uni- 
form, and each body has its own, which is often one of its 
most characteristic marks. Thus it is the melting of ice, 
and not the freezing of water, that gives the constant tempera- 
ture of 32°. By no contrivance can we raise the tempera- 
ture of ice above 32° ; nor can any other solid be heated above 
its melting point and remain a solid. Some substances, in 
melting, pass at once, like ice, to a state of perfect fluidity ; 
others have an intermediate pasty state. The following ta- 
ble contains the melting points of a few bodies at both ends 
of the scale : 



Mercury, —39° 


Zinc, 7730 


Potassium, -\-l3Q 


Silver, 1873 


Newton's Alloy, 212 


Gold, 2016 


Tin, 442 


Cast Iron, 2786 


Lead, 612 


Platina, (above) 3280 



§ 113. Diminution of volume in a body will cause a por- 
tion of the latent heat to become sensible. Thus, numerous 
blows will condense iron or gold, and so much heat will be 
evolved, that blacksmiths in this way sometimes kindle their 
fires. Water poured on quicklime combines with it, with 
the escape of much heat ; the water in this case taking on 
the solid form. Sulphuric acid and water, when mingled, 
give out great heat, and the bulk of the mixture is less than 
that of the two before mixing. In short, liquefaction is always 
a cooling process, and solidification a heating one, to all sur- 
rounding bodies. A certain quantity of heat may be consid- 
ered as necessary to preserve each body in its natural condi- 
tion : if it be condensed, less is required, and it gives out 



What is the greatest cold thus produced? § 112. What is said of 
the melting points ? Name some examples of extremes from the table. 
§ 113. How does diminution of volume affect the latent heat of bodies? 
Name some examples. 



VAPORIZATION. 83 

the excess ; and if expanded, it absorbes more. We must 
not forget that Dr. Black, of Scotland, was the first who made 
known to us the beautiful philosophy of latent heat, and all 
the phenomena of liquefaction and vaporization. 

^114. Difference hetvoeen heat and temperature.-— lli^ easy 
to see, from what has been said, that the thermometer can- 
not tell us any thing of the amount of heat in a body, since the 
latent heat is quite insensible to any thermometrical test. 
We speak more properly, then, when we say that we know 
the temperature of a body, than to say we know its heat. 

6. Vaporization. — The boiling points of Bodies. 

§ 115. A continued flow of the heat which melted the ice 
(§ 108) into water, will also turn the water into vapor or 
steam. The phenomena which attend this physical change 
are not less curious or instructive than the last. 

If we place a known quantity of water over a steady 
source of heat, we shall see the thermometer indicating each 
moment a higher temperature, until, at 212°, the fluid boils ; 
after which, the thermometer indicates no further change, 
but Bemains steadily at the same point until all the water is 
boiled away. Let us suppose that, at the commencement 
of the experiment, the temperature of the water was 62°, 
and that it boiled in six minutes after it was first exposed 
to the heat : then the quantity of heat which entered 
into it each minute was 25°, because 212°, the boiling point, 
less 62°, (the initial temperature,) leaves 150° of heat ac- 
cumulated in six minutes, or 25° each minute. Now if 
the source of heat continue uniform, we shall find that in 
forty minutes all the water will be boiled away ; and hence 
there must have flowed into the water, to convert it into 
steam, 25° X 40== 1000°. One thousand degrees of heat, 
therefore, have been absorbed in the process, and this con- 
stitutes the latent heat of steam. What we have already 
said on the latent heat of liquids will render this more clear. 
So much heat was imparted to the water, that if it had been a 
fixed solid, it would have been heated to redness ; and yet 
the steam flowing from it, and the fluid itself, had during the 
whole time only a temperature of 212°. 
___^ ■ » 

Who first made known these laws? § 1 14. Distinguish between heat 
and temperature. § 115. What takes place when we heat water? Ex- 
plain the process and the amount of heat absorbed by boiling water 
What do you call this heat? 



84 



HEAT. 



§ 116. The large amount of latent heat contained by 
steam, becomes again sensible on its condensation to water. 
This enables us to make great use of steam as a means of 
conveying heat. The steam, in fact, takes up a large quan- 
tity of heat, and transports it to the point where we wish it 
applied. One gallon of water converted into steam, at the 
ordinary pressure of the atmosphere, will raise five gallons 
and a half of ice-cold water to the boiling point. In this way 
we can boil water in wooden tanks, heat large buildings by 
steam-pipes, and make numberless other useful applications 
of steam-heat in the arts. 

§ 117. The distillation of water (or any other fluid) affords 
a good illustration of the quantity of latent heat conveyed 
away in the vapor. In the arrangement here figured, a glass 
retort (R) is made to contain a quantity of water, which is boil- 
ed by a lamp below, the vapor (steam) is conveyed by the bent 

neck to a receiving-ves- 
sel, in which it is conden- 
sed, being surrounded by 
cold water or ice poured 
into the dish placed to sup- 
port it. After the water 
boils in the retort, its tem- 
perature does not rise any 
further, but the vapor con- 
veys the heat of the lamp 
over to the condenser. The 
water which surrounds it 
will grow rapidly hot from 
the latent heat of the steam, 
rendered sensible by its 
reconversion into water. 
For this reason the condensing-water must be frequently 
changed. In metallic stills, the condenser is along metallic 
tube, bent into a spiral, (called a worm,) diXidi surrounded by 
cold water. 

§ 118. The latent heat of steam, which maybe set down 
at about 1000°, (although it is stated more accurately at 967°,) 
is greater than that of any other known fluid. The latent 

§ 116. How does the latent heat of steam again become sensible ? How 
much ice-cold water will one gallon turned to steam boil? § 117. How 
does the process of distillation illustrate this? § 118. How does the 
latent heat of steam compare with that of the vapor of other fluids? 




VAPORIZATION. 



85 



heat of fluids has no connection with their boiling point ; 
since many liquids which boil at high temperatures have 
little latent heat, and the reverse. The annexed table shows 
the boiling points and latent heats of the vapor of several 
common liquids. 



Liquids. 


Boiling Point. 


Latent Heat of Vapor. 


Water, 


2120 


9670 


Alcohol, 


172 


442 


Ether, 


96 


302 


Petrolium, 


320 


178 


Oil of Turpentine, 


314 


178 


Nitric Acid, (strong,) 


248 


532 


Ammonia,* (liquid,) 


140 


837 



^119. Boiling or Ebullition happens in a liquid when it 
becomes so hot that its vapor can rise in bubbles to the sur- 
face, and escape uncondensed by the atmospheric pressure, 
or the temperature of the fluid. The elasticity (or tension) of 
the vapor then becomes greater than the united pressure of 
the fluid and the air. When boiling is vigorous, a great num- 
ber of these bubbles of uncondensed vapor rise to the sur- 
face at the same instant, and the liquid is thrown into violent 
agitation. If a vessel containing cold water be heated sud- 
denly, the lower surface receives the most heat ; bubbles of 
vapor are formed, and rise a little way, when, meeting the 
colder water, the vapor is at once condensed, and the liquid, 
before sustained by the elastic vapor, falls with a sudden jar 
on the bottom of .the vessel, producing a series of little ex- 
plosions. This may be well seen in a glass flask suddenly 
heated by a lamp. When the heat is graduallyapplied, it is 
so evenly, and quietly distributed that this eflect is not per- 
ceived. 

The boiling point is much afiected by the nature of the 
vessel. In a metallic vessel, water boils at 210° and 211°. 
If a glass vessel is coated inside with shellac, water boils in it 
at 21 1° ; but if it be thoroughly cleaned with sulphuric acid, it 
may be heated to 221° or more, without the escape of bub- 
bles. A few grains of sand, or a little fragment of wire, or a 



Is latent heat connected with the boiling point ? 
the table. § 1 19. What is boiling ? Illustrate this. 
of the vessel affect it ? 



Illustrate this from 
How does the nature 



* Specific Gravity, 0*945. 
8 



86 HEAT. 

small piece of charcoal, will, however, at once equalize 
these differences, and cause ebullition at 212^ to take place 
quietly. This simple means will prevent the unpleasant jar 
from sudden escape of vapor, and frequent fracture of the 
vessel. 

§ 120. The pressure of the atmosphere determines the boil- 
ing point of fluids ; and w^hen we speak of the boiling point, 
we always mean ebullition under the ordinary pressure of the 
air, or 30 inches of the barometer, (§ 33.) It follows, there- 
fore, that by a diminution of pressure, water may be made to 
boil at a much lower temperature than 212°. In ascending 
high mountains, the boiling point falls with the elevation, from 
the diminished pressure of the air. On this account, a diffi- 
culty is experienced at the Hospital of Saint Bernard, 
on the Swiss Alps, in cooking eggs and other viands in 
boiling water. This place is 8400 feet above the sea, and 
water boils there at 196° ; on the summit of Mount Blanc, it 
boils at 187°. We see that it is the temperature, and not the 
boiling, which performs the cooking. The Rev. Dr. Wollas- 
ton contrived an instrument to determine the height of 
mountains by the boiling point. He found an ascent of 530 
feet to be equal to a decrease of 1° in the boiling point; 
and with a thermometer having large spaces, accurately sub- 
divided, xoW ^^ ^ degree may be read. 

§ 121. Boiling under Diminished Pressure. — A paradoxi- 
cal experiment, of easy performance, gives a very good illus- 
tration of the phenomena of boiling under diminished press- 
ure. A small quantity of water is boiled in a glass retort, 
(R, § 117,) or in a bolt-head, like that in the following 
figure : when the water has boiled a short time, a good 
cork, previously well fitted to the orifice, is firmly inserted, 
and the vessel removed from the heat. It may now be 
supported in an inverted position, with the mouth under 
water, as in the annexed figure. The boiling will, to our 
surprise, still continue, and more rapidly than before ; and 
if we attempt to check it by cold water poured on the ball, 
we shall only provoke it to boil more vehemently. A little 
hot water will, however, at once arrest the boiling of the 



§ 120. What influences the boiling point? Mention the boiling point 
of water on Mount Blanc, and the elevation necessary to produce 1° of' 
difference in the boiling point. § 121. Explain the experiment in this 
paragraph of boiling under diminished pressure. 



VAPORIZATION. 



87 



confined fluid. In this case, the air was driven out of the 
vessel on the first boiling of the water, and as we closed 
the orifice, while the steam was still issuing, 
there evidently could be only the vapor of 
water in the cavity. As this condenses 
from cooling, the pressure on the water di- 
minishes, and it boils more easily from the 
heat it still contains ; the affusion of cold wa- 
ter, by producing a more perfect condensa- 
tion, occasions a more violent ebullition. The 
hot water, however, increased the elasticity 
of the uncondensed vapor, and repressed the 
boiling. These alternations can be produced 
as long as any sensible heat remains in the 
water in the vessel. When cold, the space 
over the water will be a good, but not perfect 
vacuum, and if we turn the water from the 
ball into the neck, it will fall like lead, with 
a smart blow and rattling sound. It is some- 
times called a water-hammer. The per- 
fection of the vacuum can be tested by with- 
drawing the cork under water ; the pressure of the atmos- 
phere will then drive in a quantity of water, equal to the 
vacuum produced by the first expulsion of the air. 

§ 122. Freezing and Boiling in a vacuum.— K little ether 
under an air-jar on the plate of the air-pump will flash into va- 
por as soon as the pressure is removed by working the pump ; 
and water may be' frozen by its own 
evaporation, over a good air-pump, 
arranged as in the figure. The 
water is contained in a watch-glass 
on a tripod, over a shallow dish of 
sulphuric acid, and the whole is covered by a low air-jar. 
On working the pump, the water evaporates so rapidly in 
the vacuum as to boil ; its vapor is instantly absorbed by 
the sulphuric acid ; and in this way both the sensible and 
latent heat are removed so rapidly, that the water is frozen 
solid while still boiling. 

Dr. J. L. Smith of Charleston, S. C, has- lately shown, 





What principles are here brought into view ? How is the absence of the 
air made evident ? § 122. How is water frozen in a vacuum ? Mention 
Dr. Smith's modification of this experiment. 




88 HEAT. 

that water may be easily frozen by its own evaporation, 
without the aid of sulphuric acid, if it is supported on a 
cork, in a cavity which is charred by a spirit-lamp, or in a 
capsule of glass or porcelain, which has been nicely coated 
with lamp-black from burning turpentine : this observation 
makes this usually difficult experiment comparatively an easy 
one to perform. 

§123. The Cryophorus, or frost-hearer, offers another 
illustration of the same facts. This little instrument, in- 
vented by Dr. 
Wollaston, is 
only a bulb of 
glass, contain- 
ing a little wa- 
ter, and connec- 
ted by a long bent tube with another bulb, or protuberance, 
which is empty ; the place over the water is a vacuum, the 
tube having been sealed when the water was boiling. On 
placing the empty stem in a freezing mixture of ice and salt, 
the vapor of the water is so rapidly condensed, as to freeze 
the fluid in the ball remote from the freezing mixture. 

§ 124. Practical application of these facts is made in the 
arts on a large scale, in manufacturing sugar. The boiling 
of the syrup is performed in vacuo, in large pans of copper, 
holding several hundred gallons, the vacuum being kept up in 
the pans by a steam-engine ; the syrup is thus rapidly boiled 
down at a temperature of 150° to 180°, without any danger of 
burning. Vegetable extracts are frequently made, and saline 
solutions boiled, in the same way. Nothing in the arts shows 
more clearly the value and beauty of scientific principles. 

§ 125. Elevation of the Boiling Point by Pressure, — If 
water is boiled in a vessel, which can be closed after the 
escape of the atmospheric air, as in the brass boiler (a) of 
the annexed figure, we can easily submit it to any desired 
degree of pressure, and thus elevate the boiling point. This 
boiler is provided with a thermometer (c) whose ball is 
within the steam cavity ; and also with a barometer tube, 
(5,) which descends into some mercury, placed in the bot- 
tom. It is supported by a tripod {f) over a lamp, (e,) and a 

§ 123. What is the cryophorus? Explain the principle of its action. 
§124. What practical application is made of these facts? § 125. How 
does pressure affect the boiling point ? 



VAPORraATION. 



89 



Stop-cock (d) cuts off the external air. As soon as the 
water in it boils, the steam accumulates, and, pressing on 
the mercury, forces it up the tube, 
against the imprisoned air. The 
relation of air to pressure has al- 
ready been explained, (^ 30.) 
When the mercury indicates 30 
inches, or double the pressure of the 
air, the thermometer will indicate 
250°-5 of heat. In this way the 
boiling point of water has been 
raised to 429^-34, or nearly to the 
melting point of tin ; the pressure 
was then 375 pounds to the inch, 
or 25 atmospheres. Mr. Jacob 
Perkins heated steam so highly, 
that a jet of it set fire to combusti- 
ble bodies. 

§ 126. The elastic power of steam 
in contact with water is limited 
only by the strength of the contain- 
ing vessel : if steam be heated with- 
out water, {not in contact with it,) 
then its elastic or expansive power 
is exactly like that of other gases 
or vapors, (§ 88.) 

§ 127. The increase of volume 
from vaporization is such, that 1 
cubic foot of water becomes 1700 
cubic feet of steam ; or a cubic inch 
of water becomes nearly a cubic 
foot of steam ; while the same quan- 
tity of alcohol and ether yield, re- 
spectively, (1 cubic foot,) 493 and 212 cubic feet of vapor. 

Water is, therefore, incomparably the best fluid from 
which to generate steam for a moving power ; for its higher 
boiling point is more than made up by the greater volume 
of its vapor, and the cost of fuel is in proportion to the la-i 




Explain the apparatus here figured. What is the boiling point of water 
under 30 inches of mercury? How high has it been raised? § 126. 
How does elevation of temperature affect steam? ^ i27. What is the 
increase of volume from vaporization of water? Of alcohol? Of ether 'f 

ft* 



90 



HEAT. 



>==^=CZ> 



tent heat of equal volumes of vapor. Thus water is superior 
to ether for this purpose, in the proportion of 2500 to 1000. 
The latent heat of steam diminishes as the heat rises, so 
that the heating power of steam at 400° is no greater than 
that of an equal volume at 212°. These facts are of the 
greatest value in the arts, and should be kept in mind. 

^ 128. The Steam-Engine, — The principle of this appa- 
ratus is simple, and easily illustrated by the simple instrument 
« annexed, which 

w^as contrived by 

Dr. Wollaston. A 

glass tube, with a 

bulb to hold a little 

water, is fitted with 

a piston. A hole 

passes from the 

underside through 

the rod, and is 

closed by a screw 

at a. This screw 

is loosened to ad- 
mit the escape of 
the air, and the water is boiled 
over a lamp ; as soon as the steam 
issues freely from the open end 
of the rod, the screw is tighten- 
ed, and the pressure of the steam 
then raises the piston to the top 
of the tube ; the experimenter 
withdraws it from the lamp, the 
steam is condensed, and the air pressing freely on the top of 
the piston forces it down again ; when the operation may be 
repeated by again bringing it over the lamp. 

In the common condensing engine, a cylinder {a) is fitted 
with a solid piston, whose rod moves through a tight pack- 
ing in the cover, and to it the machinery is attached. A 
pipe (c?) brings the steam from a boiler to the valve arrange- 
ment, (c,) by which the steam is admitted, alternately, to 
the top and bottom of the cylinder ; and also an alternate 

§ 128. Explain the principles of the steam-engine from Dr. WoUaston'a 
instrument. Explain the general structure of the condensing engine from 
the figui'e. 





VAPORIZATION. 91 

communication is opened with the condenser, (b.) Thus, 
when the steam enters at the top, (in the direction of the ar- 
row,) that at the bottom of the piston is driven through the 
lower opening to {b) where it is condensed. The valves 
are moved at the right instant by the machinery. 

§. 129. Evaporation from the surface of liquids takes place 
at all temperatures, whereas ebullition, it will be remembered, 
occurs only at a particular temperature for each fluid. Even 
snow and ice waste by evaporation, at temperatures too low 
to melt them. Mercury rises in vapor, even at the temper- 
ature of 60° ; for Dr. Faraday found at that temperature a 
slip of gold-leaf suspended in a close vessel was whitened 
by amalgamation with the vapor of the mercury. 
The state of the atmosphere as to dryness and 
pressure influences natural evaporation, and this 
is greatly increased by heat and a rapid wind. It 
must be remembered that all the water which falls 
to the earth in snow and rain has arisen in evap- 
oration. That natural evaporation takes place 
only from the surface is proved by its being en- 
tirely prevented by a film of oil on the surface of 
the fluid. 

^ 130. Influence of Pressure on Evaporation. — 
If we introduce a few drops of water into a ba- 
rometer tube, filled as usual, the level of the mer- 
cury in the tube will be reduced by the vapori- 
zation of a part of the water. The tension of the 
vapor will be inc^-eased, by a rise of temperature : 
thus we may slip a larger tube over the barometer 
tube, the lower end of which dips under the mer- 
cury ; we can then surround it by hot water, pour- 
ed into the intervening space. The vapor of the 
confined water will force down the column of 
mercury in direct proportion to the temperature ; 
and by means of a thermometer and a scale of 
inches we can tell exactly the tension of the vapor 
of water for every temperature under 212°. 

^131. Maximum Density of Vapors. — If we near- 
ly fill with mercury three barometer tubes closed at one end, 

§ 129. What is the difference between evaporation and ebullition? 
§ 130. How does pressure affect evaporation ? How is the tension of 
vapor measured ? 





92 HEAT. 

and into the open end of one pour a little ether, into the second 
some alcohol, and into the third some water, and then invert 
them with their mouths beneath mercury, we shall see, on 
withdrawing the finger from the open end, 
that the mercury will be depressed least by 
the water, more by the alcohol, and most of 
all by the ether, (about 10 inches at 60°.) 
The addition of more of each fluid will have 
no effect in lowering the mercury, the tem- 
perature remaining the same. There is, 
therefore, a point of density of the vapor 
which cannot be passed without again con- 
verting it to a liquid. This is easily shown 
by inclining the tube containing the ether 
out of a vertical position ; the more horizon- 
tal it becomes, the less ether can remain in 
vapor, because the increased pressure forces 
it into a fluid state. The same fact is beau- 
tifully shown in the annexed figure, where the 
barometer-tube with ether is depressed in a 
deep cistern of mercury. The film of liquid 
ether on the surface of the mercury in the 
tube is seen to increase as the tube descends, 
until it is all reconverted to a fluid ; on dimin- 
ishing the pressure of the finger, the liquid 
ether again flashes into vapor. •The weight 
of 100 cubic inches of aqueous vapor at 
212°, in the greatest state of density ever 
obtained, is 14-962 grains ; while the same 
at 32° is only -136 grains. The point of 
maximum density of a vapor is also lowered by 
cold as well as by pressure, and when these 
two effects are united, we can convert many 
gases, which are quite permanent at the com- 
mon pressure and temperature of the air, into fluids, and 
even to solids ! 

§ 132. Diffusion of Gases and Vapors. — The vapor of 
water will rise and fill a confined vessel of air, as an air- 
jar, and have the same tension as if no air were present. 
It will take a longer time to do it, but as much will ulti- 

§ 131. What is the maximum density of vapors ? Illustrate this from 
the figure. 



VAPORIZATION. 93 

mately rise as if the space were a vacuum. The air seems 
to be an impediment to the rapid rise of the vapor, but not 
in any degree to prevent it. On the same principle, prob- 
ably, is explained the curious and important fact, that, when 
different gases are in contact, they will not remain separate, 
but will soon mingle uniformly, even against the force of 
gravity. Our atmosphere, for instance, is composed of two 
gases, which are by weight in the proportion of 976 to 1130, 
and we might suppose that the heavier would be at ^ 
the bottom, as would be the case in two such liquids 
as water and ail. But this is not so. If we connect 
together by a tube two bottles, containing, one a light 
gas, (hydrogen,) and the other a heavier gas, (oxygen,) 
and place the light one {h) uppermost, in a few hours 
we shall find them perfectly commingled ; as may be 
proved by the fact, that the mixture will explode vio- 
lently on touching a match to the open mouth of one 
of the vessels, which we know a mixture of these 
two gases will always do. The same effect will 
take place through a very fine tube, or even through 
a plug of plaster-of-paris, or through a membrane, as 
of gold-beater's skin. The degree of condensation of 
the air or vapor has no effect in the operation of the 
law or the uniform diffusion of gases. 

§ 133. Dew-Point. — Watery vapor is never absent from the 
air ; but its quantity is very variable, depending on the causes 
already named, (§ 129.) When the air is highly charged with 
humidity, it deposits dew on any substance colder than itself. 
A glass of iced water in summer is immediately covered with 
a copious coat of condensed vapor from the surrounding air. 
When a warm, humid morning succeeds a cool night, we see 
the pavements and walls of the houses reeking with depos- 
ited water, as if they had been drenched with rain. If we 
drop bits of ice into a tumbler of water having the same tem- 
perature with the air, and watch the fall of a thermometer 
placed in it, we can note with accuracy the temperature of 
the water, when it has cooled so far that dew begins to be 
deposited on the clean surface of the glass. This tempera- 
ture is called the dew-point ; and the number of degrees be- 
tween the temperature of the air, and of water cooled to that 

§ 132. Mention the facts relating to the diffusion of vapors and gases. 
Illustrate this. § 133. AVhatis the dew-point ? 



94 



HEAT. 



degree that dew begins to deposit, is an accurate indication 
of the actual dryness of the air. The nearer the dew-point 
is to the temperature of the air, the more moisture does it con- 
tain, and the reverse. In this climate, in summer, this differ- 
ence amounts often to 40° or more, and in India it has been 
known to be as much as 61° ; that is, with an external tem- 
perature of 90°, the dew-point has been seen as low as 29°. 
The amount of moisture in the air has a great influence on the 
indications of the barometer, and it is always requisite, in 
making barometrical observations, to make a correction for 
the tension of the vapor of water in the air. 

«^ 134. Hygrometers* are instruments to determine the 
amount of moisture in the air. One much used is called 
the wet bulb hygrometer, and consists of two sim- 
ilar delicate mercurial thermometers, the bulb 
of one of which is covered with muslin, and is 
kept constantly wet by wa- 
ter, led on to it by a string 
from a tube in the centre. 
The evaporation of the water 
from the wet bulb reduces 
the temperature of that ther- 
mometer to which it is at- 
tached, in proportion to the 
dryness of the air, and con- 
sequent rapidity of evapora- 
tion. The other thermome- 
ter indicates the actual tem- 
perature, and the difference 
being noted, a mathematical formula enables us 
to tell pretty nearly the dew-point. 
But the most delicate and beautiful instrument for this use 
is that of Mr. Daniell, which is constructed on the principle 
of the crt/ophorus, (§ 123.) It is well represented in the an- 
nexed figure, (a.) The long limb ends in a bulb which is 
made of black glass, that the condensed vapor may be more 
easily seen on it. It contains a portion of ether, into which 




How does it indicate the dryness or humidity of the climate? § 134. 
What are Hygrometers? Describe the wet bulb. Describe the Hy- 
grometer of Prof. Daniell. 



* From the Greek, hygroSf moisture, and metrOy I measure. 



VAPORIZATION. 95 

dips the ball of a small and delicate thermometer contained in 
the cavity of the tube. The short limb carries an empty- 
bulb, (both are vacuous,) which is covered with muslin. On 
the support is another thermometer, by which we can read 
the temperature of the air. When an observation is to be 
made by this instrument, a little ether is poured on the mus- 
lin : this evaporates rapidly, and of course reduces the tem- 
perature of the other ball, (§ 122.) As soon as this has 
fallen to the dew-point, the moisture collects and is easily 
seen on the black glass. At this instant, the temperature 
indicated by the thermometers is noted down, and the dif- 
ference gives us the true dew-point. 

§ 135. The Spheroidal state of bodies, as it is called, is a 
curious and instructive instance of the low conducting power 
of vapors. When water or any other liquid (and many so- 
lids) are projected in drops on a surface, heated consid- 
erably above its boiling point, it will assume a spheroidal 
form, roll about with activity, and evaporate with extreme 
slowness. Water assumes this condition at 298° ; and a 
grain and a half of water in this state at 392"^ requires 3*30 
minutes to evaporate : at a dull red heat, the same quan- 
tity will last 113 minutes, and at a bright red, 0'50, the 
rate of evaporation increasing with the temperature. The 
water, in these experiments, does not touch or wet the hot 
surface, but is kept at a sensible distance from it by the 
elastic force of an atmosphere of its own vapor. This vapor 
is a non-conductor, and its formation abstracts the sensible 
heat from the fluid ; so that, in spite of the nearness of the 
red-hot metal, the temperature of the fluid is found to be 
always lower than its boiling point, being, for water, 206°, 
for alcohol, 168°, and for ether, 109°. A modification of 
this process enables us to perform the wonderful experi- 
ment of freezing water in a white-hot crucible, by the aid 
of liquid sulphurous acid in the spheroidal state. All 
bodies, solid as well as fluid, as far as the experiments of 
M. Boutigny have gone, have assumed this state, when 
properly situated. 

^ 136. Liquefaction and Solidification of Gases. — We have 
said that, by the united aid of cold and pressure, many gases 

§ 135. What is meant by the spheroidal state ? How does it ilhistrate 
these principles? Explain the experiments mentioned in this paragraph. 
Is the temperature of the fluid in this state as high as its boiling point ? 




96 HEAT. 

have been made fluid, and even solid. No degree of mere 
pressure, not even 50 atmospheres, (or 750 lbs. to the square 
inch,) can alone produce this result. But by joining the two 
causes, Dr. Faraday has succeeded in reducing fifteen aeri- 
form bodies to the fluid or solid state. The simple appara- 
tus required for many of these results, is only a small tube of 

glass, bent as in the fig- 
ure, at an obtuse angle, in 
v^hich are placed the ma- 
terials for generating the 
gas; for instance, powder- 
ed bicarbonate of soda and water in one end, and sulphuric 
acid in the other, to generate carbonic acid gas ; they are 
separately introduced, and the tube then sealed by the blow- 
pipe. On reversing the position of the tube, the acid can 
be made to run down on the carbonate of soda, and the car- 
bonic acid gas wiJl be set free, but cannot escape from the 
tube. The empty end is then placed in a freezing mixture, 
and the gas is condensed into a liquid by its own pressure. 
Some hazard attends these experiments, and the operator 
should be protected by gloves and a mask of wire-gauze ; 
for the tubes occasionally burst under the enormous press- 
ure, and might wound the operator severely. Carbonic acid 
treated in this way becomes a clear transparent crystalline 
solid, at temperatures below —-71°, at which point it melts 
into a perfectly limpid fluid, which is not so heavy as the 
solid. M. Cagniard de la Tour has shown the most re- 
markable fact, that at a certain temperature and pressure, a 
liquid becomes a clear transparent vapor, or gas, having the 
same bulk as the liquid. At this temperature, or one a little 
greater, no additional pressure, however great, would con- 
vert the gas into a liquid. M. Faraday thinks that this 
state comes on with carbonic acid at about 90°, and with 
a pressure above 50 atmospheres. 

^ 137. Liquefaction and Solidification of Carbonic Acid. — 
A French gentleman, M. Thilorier, contrived an apparatus 
for condensing carbonic acid on a large scale. It was in the 
main like that figured in the margin : g is the generator of 
the gas, a strong cast-iron vessel, hung by centres on a frame, 
(/';) in it is put the requisite quantity of carbonate of soda 

§ 136. How are gases made fluid or solid? Explain the process. 
What haa M. Cagniard de la Tour shown ? 



VAPORIZATION. 



97 




and water, and a tube (a) of copper, holding an equivalent 
amount of strong sulphuric acid; the cap is strongly screwed 
in, and the position of the appa- 
ratus inverted, by turning it over 
in the frame ; the acid then runs 
out among the carbonate of so- 
da, and an enormous pressure is 
generated by the successive 
portions of gas enplved ; after 
a time, when the gas is no lon- 
ger generated, the generator 
is connected by a metallic tube, 
with the receiver, {r ;) stop- 
cocks of peculiar construction 
are fixed on the top of both 
vessels, and being opened, the 
liquid gas is found at r, which 
is cooled by a freezing mixture, for the purpose of condens- 
ing it. In this way, charge after charge of the liquid gas is 
accumulated in r. It can then be drawn off by a jet (j) 
secured to the top, which jet enters a metallic box, (b,) having 
perforated wooden handles. The rapid evaporation of the 
condensed gas, here absorbs so much heat, that a considera- 
ble portion is converted to a fine white solid, like dry snow. 
The author has repeatedly formed balls of this snow of con- 
siderable size. When thus made solid, it wastes away very 
slowly, and may be handled and transferred with ease. If 
suff*ered to rest oh the hand, however, it destroys the flesh, 
like a hot iron. It is now in a condition similar to the 
spheroidal state, {§ 135 ;) being surrounded by an atmos- 
phere of its own vapor, the radiation of heat to it from sur- 
rounding bodies is cut ofif, and it assumes the very low tem- 
perature of — 148^. If it is wet with ether in a capsule 
containing mercury, the latter is frozen solid, and can then be 
hammered with a wooden mallet, and drawn out like lead. If 
it is moistened with ether in vacuo, with certain precau- 
tions, the greatest degree of cold yet observed is produced ; 
viz : 174^ below zero of Fahrenheit. The greatest cold 
before known was — 148^, and the greatest natural cold 
ever recorded by man was — 60°, found by Captain Ross 



§ 137. Describe M. Thilorier's apparatus for condensing carbonic acid. 
What temperature has been reached by aid of this condensed gas ? 

9 



98 ELECTRICITY. 

in his polar voyages. But Faraday thinks that we have the 
means in our power, by the use of the liquid nitrous oxyd 
gas, of producing much lower temperatures. 

We see now how entirely the gaseous, liquid, and solid 
states of bodies are dependent on heat and pressure. It 
is more than probable that all the bodies now known to us 
as permanent gases may be reduced to the fluid or solid 
state, by means similar to those which have already been 
used. ^ 

IV. ELECTRICITY. 

§ 138. There is a remarkable power inherent in all things, 
which we call electricity,'^ and without which, so far as we 
know, matter cannot exist. It has been classed with light 
and heat, as an imponderable agent, and is doubtless very 
closely related to, if not identical with, them ; the three being, 
perhaps, only modifications of one and the same power. If 
not itself material, it is so intimately connected with mat- 
ter, as to be evolved, in some form or degree, with every 
change, either mechanical or chemical, which matter un- 
dergoes. As was said of heat, (§ 69,) we know it only by 
its effects, as manifested on or through matter. We shall 
consider this power under its most remarkable forms of ex- 
istence or manifestation, regarding them all, however, as 
modifications only of one and the same power. These 
are, (1,) the FAQcinQiiy o{ Magnetism ; (2,) that of Friction, 
or Statical Electricity ; (3,) that of Chemical Action, Gal- 
vanism, or Voltaism, called also. Dynamical Electricity ; 
and (4,) Thermo-electricity, or Electricity from Heat. 

1. Magnetic Electricity, or Magnetism. 

§ 139. Lode-stone.^ — A kind of iron-ore has been known 
from remote antiquity, which has the property of at- 

§ 138. What is said of electricity? How is it classed? How divided, 

(1 ?) (2 ?) (3 ?) (4 ?) § 139. What is the lode-stone. 

* From the Greek, electron, amber, the substance in which this power 
was first noticed by the ancients, more than 600 years B. C. Modern 
philosophers have given the name of the substance to the unknown 
power. 

t Sometimes spelt improperly ZortcZ-stone. It is from the Saxon Icsden, 
to lead or direct. 



MAGNETIC ELECTRICITY. 



99 




trading to itself small particles of iron, and which is called 
the lode-stone. By touch, it can impart its virtues to iron 
and steel, and also in a slight degree to cobalt and nickel. 
As it abounded in Magnesia, (a province of ancient Lydia,) 
it was called by Pliny, magnes, and hence magnet, A bar or 
needle of steel, which has received the magnetic influence, 
when suspended on a point, as in the figure, ^ 
will be found to have a directive tendency, by 
which one end turns invariably to the north. 
The terms, + and — , (plus and minus,) 
are also used to indicate the north and south 
poles. The needle is, therefore, said to 
have polarity, and the end turning north is 
commonly called the north pole, and the other end the south 
pole. If we bring the north end of a magnetic bar near 
to the similar end of the suspended needle, .,_^^^^^^ - , ^ 

the latter will move away, as indicated by the ^^ '^" 

arrows, being repelled by the similar power of the bar. If, 
however, we bring the end N, towards the opposite end of 
the needle, S, it will be attracted to the bar, and strive to 
move as near to it as possible. The reverse is, of course, 
true of the opposite end of the bar. If, in place of a mag- 
netic bar, we had used a bar of unmagnetic iron, we should 
have found both ends of the suspended needle equally, but 
less powerfully, attracted by it. We thus learn, (1,) that the 
magnet has polarity, and (2) x\\d,\. poles of the same name re- 
pel, and those of opposite names attract, each other. This 
is the simple and important law of magnetic action. 

§ 140. Induction of Magnetism. — The manner in which 
a magnet, or lode-stone, imparts its own power to surround- 
ing substances, is called induction, and 
those bodies capable of manifesting 
this power are said to be magnetized 
by the inductive influence. Thus, a se- 
ries of bars of iron laid about a mag- 
netic bar, as in the figure, will all be- 
come magnetic by induction, while 
they are under the influence of the 
magnet ; and in obedience to the law 
just stated above, their ends next the 

Explain its action. Can its virtues be imparted, and to what ? What 
do we know of the suspended needle, (1?) (2?) § 140. AVhat is induc- 
tion of magnetism? Jllustrate this. 




100 



ELECTRICITY. 



are all S, and their remote ends all N. Every mag- 
g net is surrounded by an atmosphere of influence, 
which has its centre in the poles of the magnet, and 
diminishes as the square of the distance, being in 
this respect like the law of gravitation. This is 
prettily illustrated by an experiment shown in the 
annexed cut. The bar magnet holds a large key; 
this can hold a second smaller than itself; this, a 
nail ; the nail, a tack ; and lastly, a few iron filings 
are held by the tack, and the whole receive their 
magnetism by induction from the bar, and each ar- 
ticle has its own separate polarity : a n and s (or + 
and — ) pole being opposed to each other at every 
junction. This effect will take place through a 
glass-plate, or a small interval of air. 

^141. Permanent Magnets. — These can be made 
only of hardened steel. Soft iron and steel are mag- 
nets only while under the power or influence of 
other magnets, and lose their own power as soon 
as removed from them. Magnetism is imparted by 
' toucli^ as it is technically called, from a previously 
existing magnet. An unmagnetic bar of hardened steel, 
when rubbed by the poles of a magnet in such a manner 
that the poles of different names shall be opposite to each 
other, will itself soon acquire polarity and magnetic power. 
Every magnet is considered as made up of a great num- 
ber of small magnets, so to speak, each particle of steel 
having polarity, and attracting and repelling every other. 
We cannot conceive of one sort of polarity existing without 
the other. Thus, in the figure, we see a magnified repre- 
sentation of this condition. 
?^ Each little magnet has its 
czHiczMi LZKB fZ3K czaa czM czM [iDM owu u and s. Tliosc 
which occupy the middle of the bar, being acted on alike 
in all directions, can show no power ; but the force accu- 
mulates toward each end, until we find the greatest power 
in the last range of particles, which we term the poles. 
If we dip a magnetic bar in iron-filings, we shall find the 



nsnsnsnsnsnsnsns 



Nc 



How is the power as regards distance ? Give an experimental illus- 
tration. § 141. How are permanent magnets made? How is the power 
supposed to be distributed ? Why have the poles more power than the 
centre ? 



j^^^^gfli^^ 



MAGNETIC ELECTRICITY. 101 

ends only attracting a tuft of the metallic particles, while 
the middle is free. Two bars, however, like the figure, 
placed together, (+ and — ,) and a sheet of pajDer laid over 
them, will attract iron fil- ...;^^;^.^vA;i;i;;;;;:v.f,v..^::=i^^^^^^ 
ings scattered on the pa- .^Mj ^^^MJIli^fe . 

per, m the way represent- '-'^^^l,. „...,......».-^g. ±! ^te^? 

ed in the figure ; here a ^''^^''''"''■' 
pair of central poles have 
power to attract the iron, which the middle part of the sim- 
ple bar had not. The particles of iron arrange themselves 
in what are called magnetic curves. If the paper is jarred, 
this effect is increased. 

^ 142. Artificial Magnets are made of all forms, the most 
common being the so-called horse-shoe magnet, shaped ■ ■ 
like the annexed figure. It is found that the power of ^ 
magnets is much increased by uniting several thin plates of 
hardened steel, each of which is separately magnetized. A 
bar of soft iron, called the keeper, is placed across the poles 
of a U magnet, to prevent it from losing power ; and if it be 
made to hold a weight nearly ^qual to its power, it will be 
found to gain strength daily, and in like manner to lose 
power if unemployed. 

§ 143. The Earth^s Magnetism.— The, earth is considered as 
a great magnet, and the magnetism which we see in bars of steel 
and the lode-stone, is the result of induction (^ 139) from the 
earth. The magnetic poles of the earth are not in the same 
points with the poles of revolution or the axis of the earth, and 
for this reason, the magnetic needle does not point to the true 
north and south, but varies from it more or less, and differs 
at different times, as the magnetic pole alters its position. 
This is called the variation of the needle, and amounts, at 
New Haven, to 6° 10', W., (in 1840,) and 
at Philadelphia, to 3° 52', W., (in 1837.) 
Moreover, as unlike poles attract each 
other, the end of the needle pointing 
north is, in fact, its south pole, viewing 
the earth as a magnet. 

The magnetism of the earth is beau- 
tifully shown by the dipping needle, rep- 

If two bars are laid together, how is it ? § 142. What forms are given 
to artificial magnets? § 143. What is said of the earth's magnetism? 
How js it shown? Is the magnetic pole coincident with the pole of rev- 
olution ? What is dip, and what variation 7 Are they constant ? 

9* 




102 ELECTRICITY. 

resented in the annexed figure. The needle (n) is sus- 
pended on the horizontal bar, (a,) so as to move in a vertical 
plane, instead of horizontally, as in the compass-needle. 
The graduated circle (c) is placed in the magnetic meridian, 
and the needle then assumes, in this latitude,* the position 
shown in the figure, dipping down at an angle of 73° 26'-7. 
Over the magnetic equator, it would stand horizontal, being 
equally attracted in both directions. At either magnetic 
pole, it would be vertical. 

The horizontal variation of the needle, its dip, and also 
its intensity, are subject to daily and local changes, from 
the fluctuation in the amount or direction of this force ; and 
daily and even hourly observations have now for several 
years been made in all parts of the world, to determine with 
accuracy the limit of these variations and the laws which 
govern them. 

^ 144. The magnetism of the earth is induced in all 
bars of steel or iron, which stand long in a vertical position. 
Tongs and black-smiths' tools are often found to be magnet- 
ized ; and the effect may be hastened by holding a bar in 
the line of the magnetic dip, and striking it on the end with 
a hammer ; the vibration seems to aid in increasing the 
magnetic force. The tools used in boring and cutting iron 
are generally found to be magnets. 

2. Electricity of Friction ; or Statical Electricity, 

§ 145. Electricity is evolved by several of the same caus- 
es which we have already (§ 69) named as sources of 
heat. Friction excites it abundantly ; chemical action still 
more so. It attends animal life, and is powerfully exhibited 
in some animals, as the torpedo : heat evolves it, while on 
the other hand heat is evolved by it ; and we have reason 
to believe that the sun's rays are perpetually exciting elec- 
trical currents in the earth. Like heat, it neither adds to, 
nor subtracts from, the weight of matter ; but unlike heat, it 
produces no change in dimensions, and does not affect the 
power of cohesion or chemical union in homogeneous bodies. 
In powerful discharges, however, it overcomes cohesion by 

§ 144. How are bars of iron and steel siffected by the earth's magnet- 
ism ? § 145. How is electricity evolved ? Contrast it with heat 

* Lat. 41<^ 18', Ion. 17^ 58', in September, 1S39. 



ELECTRICITY OF FRICTION. 



103 



rending or fusion. It can act in opposition to gravity, and 
holds an important power over the constituent atoms of mat- 
ter. All matter is subject to its influence, and it can be 
transferred from an excited body to one previously in a neu- 
tral state. 

§ 146. Electrical Excitement, — If we briskly rub a glass 
tube with warm and dry silk, and bring it near to any light 
substance, (as a feather suspended by a thread, j 

a flock of cotton, some shreds of silk,) or, as o 

in the figure, to two balls of pith, suspended on /K 
a hook by delicate wire, the light substances / ii \ 
will at first be strongly attracted to the tube, < | 1 V;- 
but in an instant will fly off* again, as if re- ' ^^ 
pelled by some unseen force, and any further effort to at- 
tract them to the excited glass will only cause their further 
removal. Each separate thread of silk and each pith-ball 
seems to retreat as far as possible from the glass tube and 
from the other threads. An artifi- 
cial head of hair or shreds of dry 
paper shows this in a striking man- 
ner, when placed in the conductor of 
an excited electrical machine. Each 
hair stands aloof from every other, 
as if instinct with hatred. If now, in 
the place of the glass tube, we use 
a stick of sealing-wax, rubbed with 
dry flannel, and present this to the 
feather, pith-ball-, or head of hair, 
which has been excited by the glass 
tube, we shall find a very strong at- 
traction manifested between them ; the light substance pre- 
viously excited by the glass, will move to the excited resin 
much more actively than a substance not previously excited 
in this way ; and two substances separately excited, one 
by the glass and the other by the resin, although strongly 
self-repellent, will attract each other with equal power. One 
of these is called vitreous, and the other resinous electricity. 
Simple as these phenomena are, they form the basis of all 
electrical science. 




§ 146. Explain the first facts in electrical excitement. How are the 
pith-balls and head of hair affected? If wax ie used in place of glass, 
what happens? What are thesejtwo electricities called ? 



104 



ELECTRICITY. 



^ 147. Electrical Polarity, — We see in the facts just sta- 
ted a strong resemblance between the two sorts of electri- 
cal excitement and the opposite powers of the magnet. 
The vitreous is to the resinous electricity as the north pole 
of a magnet is to the south. Hence we call the vitreous 
the positive electricity, and the resinous the negative elec- 
tricity. Each particle of matter thus influenced by electrical 

excitement must have 
polarity, like the mag- 
netic needle, attract- 
ing and repelling, ac- 
cording as it is acted 
on by like or unlike 
forces. Thus a row 
of pith-balls, as in the figure, will all become excited by in- 
duction, or influence, and the signs plus and minus will ex- 
plain how they stand related to each other. Magnetism, as 
it is usually understood, is confined to two or three metals ; 
while electricity can, with proper precautions, be excited in 
all substances. 

We cannot conceive of one sort of electrical excitement 
existing without the other ; thus the glass tube is +, but the 
silk which rubs it is — , and vice versa, the resin is — , but 
the flannel is + . 

^ 148. Electrical Equilibrium. — All cases of electrical ex- 
citement are due to a disturbance of the electrical equilibrium^ 
or balance of power, which, aside from disturbing causes, 
naturally exists among surrounding bodies ; and the intensity 
of the electrical action is directly proportioned to the amount 
of that disturbance. The more unlike in electrical state a 
body becomes to surrounding substances, the more energetic 
will be the display of electrical power. The opposite states 
are, however, always in such proportion as exactly to neu- 
tralize each other in any two substances which have been 
mutually excited ; as glass and the silk rubber. These 
statements are correct, according to either of the two pre- 
vailing views of the ultimate nature of electricity. 

§ 149. Theories of Electricity. — Two theories are in 



§ 147. What analogy do we see between the two electricities and the 
magnet? What names do we give to them ? Can one sort of electricity 
exist without the other? § 148. What is electrical equilibrium ? 



ELECTRICITY OF FRICTION. 105 

vogue to explain the ordinary phenomena of electricity. 
The first is that proposed by our distinguished countryman, 
Dr. Franklin, (and called the Franklinian Hypothesis^) which 
is very simple and ingenious. He supposed there was a 
simple, subtle, and highly elastic fluid, which pervaded all 
matter. This fluid is self-repellent, but attracts all matter, 
or its ultimate particles ; these particles of matter he con- 
sidered as also self-repellent, when deprived of, or pos- 
sessing more than, their natural quantity of electricity, and 
attractive, when they are in opposite conditions. In the nat- 
ural state of bodies, this fluid is uniformly distributed, and 
its increase or diminution produces electrical excitement. 
Accordingly, when a glass tube is rubbed with a silk hand- 
kerchief, the electrical equilibrium is disturbed, the glass ac- 
quires more than its natural quantity, and is over-charged, 
the silk retains less, and is under-charged. 

The second hypothesis is that of Du Fay, who imagined 
that electrical phenomena were due to two highly elastic, 
imponderable fluids, the particles of which are self-repel- 
lent, but attractive of each other. These two fluids exist 
in all unexcited bodies in a state of combination and neu- 
tralization, when no electrical phenomena are seen. Fric- 
tion occasions the separation of the fluids, and the electri- 
cal excitement continues until an equal amount of opposite 
electricity to that excited has been restored to it. 

According to Dr. Franklin's theory, the two states are 
denominated positive and negative ; according to Du Fay, 
they are distinguished as vitreous and resinous. We can use 
either of these terms indifferently, however, without commit- 
ting ourselves to either theory, both of which cannot be true. 
The real use of such terms is, to enable us to obtain clearer 
notions of the relation of the several phenomena ; and the 
hypothesis which they express serves as a thread of philos- 
ophy on which to string our separate facts. 

§ 150. Conductors and Insulators of Electricity. — The 
pith-balls or glass tubes, which have been electrically exci- 
ted, return to a natural state very slowly indeed, if left un- 
touched, in dry air. But the hand, or a metallic rod, will 
at once restore them to the unexcited state, while dry silk, 



§ 149. Name the two theories of electricity. What is the Franklin- 
ian hypothesis ? What is Du Fay's view? What is the use of such 
theories ? 



106 



ELECTRICITY. 



glass, and resin, will not remove the excitement. Bodies 
are, therefore, divided into conductors and non-conduc- 
tors of electricity, or more properly, into good and bad 
conductors. The electrical discharge takes place through 
good conductors, (as the metals,) with an inconceivable 
velocity, which can be compared only to the velocity of 
light. Indeed, this velocity is usually stated as greater than 
that of light. Among good conductors we have, in the order 
of their conducting power, the metals, charcoal, plumbago, 
and various fused chlorides, strong acids, water, damp air, 
vegetable and animal bodies ; among had conductors are 
spermaceti, glass, sulphur, fixed oils, oil of turpentine, resin, 
ice, diamond, and dry gases. The latter substances are 
also called insulators^ because by their aid we can insulate 
or confine electricity. 

^ 151. Electroscopes, or Electrometers, — The ^mcZ of elec- 
trical excitement in a body is ascertained by a very simple 
apparatus, called an electroscope. The pith-balls (^ 146) 
serve this purpose very well. We excite them by electri- 
city of a known kind, as of an excited glass tube brought 
into actual contact with them, and then we bring near them 
the body whose electrical name we wish to learn : if they are 
still further repelled, we conclude that the 
body in question has vitreous or positive elec- 
tricity ; but if they are attracted, we conclude 
that the reverse is true. The gold-leaf F^lec- 
trometer is, however, a much more sensitive 
and delicate test of electrical excitement, and 
consists of two leaves of gold, suspended in an 
air-jar, and communicating by a wire with a 
small plate of brass ; the approach to this 
plate of a body in any degree excited, will 
occasion an immediate movement of the gold- 
leaves, from which we can tell the nature of the excitement, 
as above described, having previously imparted to the gold- 
leaves a particular kind of electricity. 

^ 152. The Electrical Machine. — The principle of the 




§ 150. What are conductors ? What are msulators? Name some of 
each. § 151 . What is an electroscope ? How do we, by means of it, as- 
certa'in the kind of electricity ? 



ELECTRICITY OF FRICTION. 



107 



common electrical machine will be easily understood, after 
what has been said. 
Two forms of this 
machine are in com- 
mon use, the cylinder 
and the plate ma- 
chine : a good view 
of the latter is pre- 
sented in the annexed 
figure ; c^ is a wheel 
of plate-glass, turned 
on an axis by a han- 
dle. The electricity 
is excited by the fric- 
tion of two cushions 
rubbers, (e, e,) 



or 

which press against 
the plate, and are 
covered with a soft 
amalgam of mercury, 
tin, and zinc, which 
greatly heightens the effect. The rubbers are connected 
with the earth by a metallic chain, [b.) The excited glass de- 
livers its electricity to several sharp points of wire attached 
to the bright brass arms, and connected with the great con- 
ductor, (o.) The conductor and plate are perfectly insulated 
by glass supports. When thus arranged, and the machine 
is turned, bright sparks of a violet color, forming lines like 
lightning, will dart with a sharp sound to any conduct- 
ing substance brought near to the great conductor. This 
is positive electricity. If negative electricity be wanted, 
we must insulate the rubbers, and, connecting the conductor 
with the earth, draw the sparks from the rubber. 

Every care must be taken in the use of an electrical ap- 
paratus, to keep it clean and smooth, and particularly free 
from moisture. Dust acts as so many points to discharge 
the fluid, and moisture deposits itself in a thin film over the 
insulators, and prevents the accumulation of power. 

§ 153. The Ley den- Jar, or Vial, is the simple means by 
which the experimenter collects and transfers a portion of 
the electricity evolved by his machine, and applies it to the 




§ 152. Explain the electrical machine. 



108 



ELECTRICITY. 




purposes of experiment. The Leyden-jar, (so called from 
the place where it was first invented,*) is only a glass bottle, 
covered inside and out with tin-foil up to the line seen in 
the figure. A brass ball communicates by a 
wire and chain with the interior coating, the 
mouth being stopped by a cover of dry wood. 
On approaching the ball to the conductor of 
the electrical machine, when in action, a series 
of vivid sparks will be received by it, and a 
great accumulation of vitreous electricity takes 
place in the interior, provided the exterior be 
not insulated. On forming a connection by a 
conductor between the interior and exterior 
surfaces, the equilibrium is at once restored by 
a rush of the opposing forces, accompanied with a brilliant 
flash of artificial lightning, and, if the hand of the operator 
is the conducting medium, a violent shock is felt, commonly 
known as the electrical shock ! A series of such jars ar- 
ranged so as to be charged by one machine, are called an 
electrical battery. 

§ 154. The Electrophorus'\ is a convenient mode of ob- 
taining an electrical spark, when no electrical machine is to 

be had, and consists of a shal- 
low tray or dish of tin, (or a 
wooden box,) the size of a din- 
ing plate, partly filled with 
melted shellac, a, or some other 
good resinous preparation, made 
as even as possible. A disc of 
brass {b) with a glass handle is 
provided, and the bed of resin is rubbed with a dry flannel 
or cat-skin ; this excites negative electricity, and the metal 
disc is then laid on the excited surface, and touched with 
the finger. A coating of positive electricity is induced on 
it, and it may be raised by the handle, and discharged by a 
conductor, giving a vivid spark, sufficient to explode gases. 




§ 153. What is the Leyden-jar, and how used? § 154. What is an 
electrophorus, and how made and used? 



* This instrument, attributed to one Cunseus, of Leyden, in 1746, 
did as much for statical electricity as the pile of Volta did for galvanism, 
t From the Greek electron and phero, I carry. 



ELECTRICITY OF CHEMICAL ACTION. 109 

The resinous electricity not being conducted away from the 
shellac, the spark may be repeated as long as the excite- 
ment lasts. 

^155. A jet of high steam issuing from a locomotive 
or other insulated steam-boiler will, with certain precautions, 
give a stream of electrical sparks more powerful than any 
electrical machine. 

This has been called hydro-electricity, and is produced by 
the friction of the hot steam on the edges of the orifice 
from which the steam issues. 

^ 156. Thunder and Lightning, — These common natural 
phenomena are due to the passage of electricity from one 
cloud to another, or from a cloud to the earth, which is 
usually attended with a brilliant flash (lightning) and loud ex- 
plosion (thunder.) Dr. Franklin first suggested and proved 
the lightning of the atmosphere to be the same thing as the 
machine electricity, and contrived an electrical kite, by 
which, with great hazard, he drew the lightning of the 
clouds to the earth.* In a thunder-storm, the electrical cloud, 
the intervening air, and the earth, represent respectively the 
inner and outer coatings of the Leyden-jar ; the air being 
the non-conductor through which the discharge finally takes 
place. 

3. Electricity of Chemical Action, — Galvanism^ or Voltaism, 

^ 157. We have found the electricity of friction, or ma- 
chine electricity, to be endued with great energy, passing 
with a vivid spark through a considerable thickness of dry 
air, and capable of being insulated by non-conductors, so as 
to be easily transferred and managed, as in the Leyden-jar. 
Moreover, we know that dryness and insulation from the 
earth are essential to its excitation, by artificial means. 
We shall now see how strongly in these, as well as many 



§ 155. What is said of the electricity of high steam? § 156. What 
are thunder and lightning? How is the Leyden-jar like the conditions 
of a thunder storm? What was Franklin's discovery about lightning? 
§ 157. What leading properties have we observed in machine electri- 
city? 



* " Eripuit coelis fulmen sceptrumque tyrannis." 
10 




110 ELECTRICITY. 

Other respects, it is contrasted with the sort of electricity 
which is the product of chemical action, and best known as 
Galvanism, or Yoltaism.* 

§ 158. Origin and Discovery of Galvanism. — Accident 
led to the discovery of the science of galvanism in ITQO.f 
Galvani:|: observed that the freshly prepared legs of a frog 
were convulsed, when brought within the 
influence of a powerful electrical machine 
in action. He at once believed that he had 
discovered in electricity the secret spring 
of life and nervous power. Yolta, however, 
reasoned, that the convulsions were in no 
way connected with animal life, but that the 
muscular contractions were excited in the 
legs of the frog by induction from the active 
machine ; this effect being produced through 
the influence of two metals, which, at the 
time, were in contact with the naked flesh. 
This experiment is easily repeated on the 
legs of a frog, from which the skin has been 
recently stripped. They are suspended by a silver or pla- 
tinum wire, or a wire of any metal, passed under the crural 
nerves, which are easily found, by gently separating the 
large muscles of the legs at a. A slip of zinc, bent so as to 
touch at the same time the toes and the wire of suspension, 
will occasion violent convulsions in the legs. This irrita- 
bility is lost soon after death. 

§ 158. When, how, and by whom, was galvanism discovered ? Ex- 
plain the experiment with the frog's legs. 



* This sort of electrical excitement is, also, frequently called the 
" electricity of contact," because actual contact of the materials employed 
is required. It is likewise called dynamical electricity, (from dunamiSf 
power,) and " current aJfinityJ' 

t Accident, properly considered, never discovered any philosophical 
principle. The minds of philosophers had been ripening for 50 years for 
Volta's discovery, and the twitching of the frogs' legs, like Newton's ap- 
ple, was only the spark which fired the train that had been long laid. 

t Prof. Galvani lived at Bologna, in Italy, and Volta of Pavia was his 
nephew and pupil ; although Galvani made the first observations, Volta 
offered the true explanation of the observations of his uncle, and by ra- 
tional experiments supported it against powerful opposition. Voltaism 
would, therefore, seem to be a more just term for the science than Gal- 
vanism. 



ELECTRICITY OF CHEMICAL ACTION. Ill 

§ 159. Voltaic Pile. — Volta sagaciously reasoned, that the 
same effects could be produced with simple metals and a 
fluid, or substances saturated with a fluid. The truth of this 
conjecture is easily verified, by placing on the tongue a sil- 
ver coin, and beneath it a slip of zinc, or a cent of copper. 
On touching the edges of the two metals so situated, we 
perceive a mild flash of light and a sharp prickling sensation, 
or twinge, giving notice of the production of a voltaic cur- 
rent. Volta arranged a series of copper and silver coins in 
a pile, with cloths wet in a saline or acid fluid 
between them. The arrangement is seen in 
the figure. The copper (c) and zinc [z) al- 
ternate with the wet cloth between. The pile 
begins with z and ends with c. On establish- 
ing a metallic communication between these 
extremes by a wire, a current of electricity, of 
peculiar characters, flows in the direction of 
the arrow on the wire.* If one hand be placed 
on each end of the pile, a shock will be expe- 
rienced, similar in some respects to that from 
the electrical machine, and yet very unlike it. If the pile 
has many members, on touching the wires communicating 
between the extremes, the shock is very intense, and a vivid 
spark will be produced, which is increased if points of pre- 
pared charcoal are attached to the ends of the wires. The 
conducting wires held together will grow warm, and even 
hot, and if a short piece of small platina wire is interposed, 
it will be heated to bright redness. Such is an outline of 
the remarkable discovery of Volta, whose pile was made 
known to the world in 1800. The principle involved in 
this arrangement is unaltered, although more manageable and 



§ 159. What was Volta's reasoning ? What instrument did he invent, 
and when ? How was it constructed ? What is its action ? 




* The iexms fluid or current ^ are used in obedience to custom ; but the 
learner should remember, that the ' fluid' is only an ideal one, as we have 
no evidence of its existence, and the wire which communicates the elec- 
trical influence does not carry any fluid, as a pipe carries water. There 
is not a particle of evidence as to the real nature of the electrical ex- 
citement produced by the action of acid water on diflTerent metals. All 
we know is, that so long as such action lasts, there is a constant produc- 
tion of an electrical excitement or influence, which we call a current. 



112 



ELECTRICITY. 




extensive forms of apparatus have supplied the place of 
the pile. 

§ 160. Simple Voltaic Circle. — A voltaic current is estab- 
lished whenever we bring two dissimilar metals, (as copper, 
silver, or platina, with zinc or iron,) into contact in an acid 
or saline fluid. Thus if we place a slip of 
copper in a glass of acid water, and beside 
it in the same vessel a slip of amalgamated* 
zinc, as long as the two metals do not touch, 
there will be no action, but on touching the up- 
per ends of the two slips of metal, a vigor- 
ous action will commence, bubbles of gas 
will be rapidly given off from the copper, 
w^hile the zinc will be gradually dissolved 
in the acid water. This action will be arrested at any 
moment, on separating the two metals. The end of the 
zinc in the acid is +, or positive, and that in the air 
— , or negative ; the copper has the reverse signs. These 
relations are expressed in the figures by the signs + 
and — , and by the direction of the arrows, showing how the 
-f- electricity of the zinc passes to the 
— of the copper in the acid ; while the 
bubbles of gas (hydrogen) set free at the 
+ end of the zinc, travel over and are de- 
livered at the — of the copper. The sec- 
ond figure shows how the current may be 
established by wires, without the direct con- 
tact of the slips. In this case the wires (as 
in the pile, ^ 159) carry the influence in the 
direction of the arrows, and the existence of the current 




§ 160. What is a simple voltaic circle? Explain the electrical rela- 
tions of zinc and copper, in and out of the acid. What is amalgamation ? 
Is contact of the metals in the vessel necessary ? Explain the second 
figure. What determines the direction of the current ? 



* Amalgamated zinc, is zinc which has been rubbed over with mer- 
cury ; this is done by dipping common sheet or cast zinc into a dilute 
acid, and while the surface is still being acted on, rubbing it with mercu- 
ry, which will at once cover the surface with a resplendent surface of 
quicksilver. Pure zinc would not need amalgamation, but all commer- 
cial zinc is impure, and the object of the amalgamation is to cover over 
the impurities, (mostly iron and charcoal,) and reduce the surface to per- 
fect electrical uniformity, so that it shall be all positive, and not a mix- 
ture of positive and negative. 



ELECTRICITY OF CHEMICAL ACTION. 



113 



and its positive and negative characters may be shown by 
the effect produced by it on a small magnetic needle, which 
will be influenced by the wires carrying the current, just as 
by the magnet ; being attracted or repelled according as it 
is above or below the wire, and in either case endeavoring 
to place itself at right angles to the conducting wire, (^ 165.) 
The direction of the voltaic current (and of course the + 
or — qualities of the metals from which it is evolved) de- 
pends entirely on the nature of the chemical action produ- 
ced. Thus if, in the arrangement just described, strong 
ammonia-water were used, in place of the dilute acid, all 
the relations of the metals and the fluid would be reversed, 
since the action would then be on the copper. But we shall 
consider the chemical effects of the voltaic circle in the 
chapter on chemical philosophy. 

^161. The Compound Voltaic Circle^ — If, in place of one 
cell, as just described, we arrange several of the same sort, 
like the three in the 
figure, not forming 
any direct metallic 
communication be- 
tween the members 
of the same cell, but 
only between those 
of different cells, 
then we shall find 
(attending to the signs + and — ) that the positive electri- 
city of the first copper will be exactly neutralized by the 
negative of the zinc of the next cell, and so on ; and we 
shall have at the terminal wires only the same quantity of 
electricity which we had in a single cell ; all the opposite 
electricities of the intermediate members being exactly 
neutralized.* 

§ 162. Quantity and Intensity, — We learn the remarkable 
fact from this statement, that, no matter how much we may 
increase the number of the members in a voltaic circle, the 




If ammonia were used, how would it be ? § 161. What is a compound 
voltaic circuit? How are the members united? Explain the relations 
from the signs -\~ and — . What do we thus discover ? 



* This form of apparatus was called the crown of cups, {Couronne de 
tasses,) being arranged in a circle. 

10* 



114 ELECTRICITY. 

quantity of electricity passing in the current is equal only 
to that evolved by a single cell. But the current which has 
passed through a number of similar cells has acquired an 
intensity exactly proportioned to the number. Thus no 
single cell, however large, would ever afford electricity of a 
tension sufficiently high to decompose water, to give the 
slightest shock to the animal frame, or produce the least 
trace of a spark. But the increase of size of the indi- 
vidual plates will enable us to produce much greater effects 
of induced magnetism, and to accumulate heat to a surpris- 
ing extent.* These effects are said to depend on the quantity 
of electricity, while the other class is said to depend on 
greater intensity given to a smaller amount of electricity, by 
extending the series, each renewal of the series acting as 
an impediment to the progress of the current, which is sup- 
posed thus to acquire new energy. 

The electricity always flows, both in simple and com- 
pound circles, from the zinc to the copper, in the fluid of the 
battery ; and from the copper to the zinc, out of the battery. 
This is important to be remembered, since the zinc is called 
the electro-positive element of the voltaic series, although out 
of the fluid it is negative ; and consequently, in voltaic decom- 
position, that element which goes to the zinc pole is called 
the electro-positive element, being attracted by its opposite 
force ; while the element going to the copper is called, for 
the same reason, the electro-negative. The compound circle, 
reduced to the simplest form of expression, would be — 
Copper — zinc — fluid — copper — zinc. 

Here the copper end is negative and the zinc positive, 
but the two terminal plates are in no way concerned in the 
effect ; so that, throwing them out of the question, we bring 
it to the state of the simple circle, which is simply — 

Zinc — fluid — copper ; 
and here we find the zinc end negative, and the copper end 
positive. 

§ 162. Explain what is meant by quantity and intensity. What ad- 
vantage is there in multiplying the series, if no more electricity is evolved ? 
What happens from the use of large plates ? How does the current al- 
ways flow in the battery? How out of it ? What electrical names then 
have the copper and zinc ? Reduce the compound circle to its simple 
form of expression. 

* Hare's calorimotor, or heat-mover, is constructed on this principle. 



ELECTRICITY OF CHEMICAL ACTION. 



115 




§ 163. Galvanic batteries are very various in form, but all 
involve the same principle. Besides those already men- 
tioned, we may briefly name a few others; and, (l,)Mr. 
Cruickshanks', called 



the " trough battery," is 
formed of double plates 
of copper and zinc sol- 
dered together, and cemented into a mahogany trough ; so as 
to form a series of tight cells, into which the acid fluid is 
poured ; the effect is greatest at the first moment of contact 
of the acid and plates, 
and the operator must 
hasten to complete his 
experiments before the 
power has materially de- 
clined. (2.) To avoid 
this inconvenience. Dr. 
Wollaston contrived the 
annexed arrangement, 
where the copper is bent 
so as to surround the 
zinc, thus doubling the 
surface compared with 
the last ; the metallic 
connections are made to a bar of wood, by means of which 
the whole series may be easily raised and lowered, in the 
porcelain or earthen-ware trough, having a separate cell for 
each pair. 

(3.) Dr. Hare, of Philadelphia, first informed us that sep- 
arate cells were not required for each pair of plates, and that 
by packing an arrangement similar to Wollaston's, in a 
frame, with varnished paste-boards between the members, 
to prevent any metallic contact, a large number of members 
might be instantaneously immersed and raised again from 
the acid fluid at one movement. The greatest economy of 
power is thus gained, and the effects are truly surprising. 
Such an arrangement is called a defiagrator^ from the energy 
with which it deflagrates or burns the metals and other 
combustible substances. There is a battery of this kind in 
the Laboratory of Yale College, consisting of nine hundred 




§ 163. Mention some of the forms of battery. 
and its disadvantages. (2.) Wollaston's improvement, 



(1.) Cruickshanks', 




116 ELECTRICITY. 

members, 4 X 12 inches, each zinc being surrounded by a 
copper case, and the whole packed as above described in 
twelve frames, and all immersed at one movement. The 
fluid used to excite this battery is usually dilute sulphuric 
acid, (I part acid to 14 or 16 of water by weight.) Its de- 
flagrations are ex- 
tremely splendid and 
energetic, and the 
arch of light (A in 
the annexed figure) 
given out at its poles, 
between points of 
charcoal, (C C,) has often been five or six inches in length. 
The power of such an instrument in chemical decomposi- 
tion is very great. 

There are many other forms of voltaic battery, but we 
have not space to mention any more, except those which 
will be named when we treat of the chemical eflects of 
galvanism, among which are some of the most convenient 
and valuable we have. As more knowledge of chemical 
terms than the student is now supposed to possess would 
be required to make them intelligible, they are described 
under the head of chemical philosophy. 

§ 164. Effects of Voltaic Electricity. — These are conven- 
iently classified under the heads, (1,) Electrical, (2,) Lumin- 
ous, (3,) Calorific, (4,) Electro-magnetic, (5,) Chemical, (6,) 
Physiological. Of these, the first three and the last have 
received as much attention as our limits will permit. The 
fifth will be considered after we have become somewhat 
familiar with the principles of chemical philosophy. We 
have then to consider, briefly, the fourth eflect of voltaic 
electricity, or — 

4. Electro-Magnetism, 

^ 165. Affects the Needle. — If a wire conveying a voltaic 
current be brought ahove^ and parallel to, a magnetic needle, 
(as shown in figure a,) the latter is invariably afl^ected, as if 



(3.) Hare's deflagrators, and their great superiority. § 164. How are 
the effects of voltaic electricity classed? § 165. How is the magnetic 
needle affected by the voltaic current ? 



ELECTRO-MAGNETISM, 



117 




the poles of another magnet had been brought near, (§ 139.) 
If the current were flowing, as indicated — ^ 

by the arrow on the wire, say to the north, ^ ' 

then the north pole of the needle will turn 
to the east ; if the current is flowing 
south, it will turn to the west. If the line 
carrying the current is placed beneath the 
needle, the same effect is produced as if 
the current had been reversed ; the needle 
turns in the opposite way to what it does ^ 

when the wire is above. The effort of the needle is to ' 
place itself at right angles to the wire, as if influenced by a 
tangential force. If the wire is bent 
in a rectangle, as in figure 6, and 
wound with silk or cotton, to pre- 
vent metallic contact and the lateral 
passage of the current from wire to 
wire, then it is evident that any cur- 
rent which may be flowing over the ^ 
wire will have to pass completely around the needle, and the 
effect which is produced will be in proportion to the num- 
ber of turns made by the wire, since its influence is doubled 
by each additional turn. In this way we can make a very 
feeble current sensible. Prof. (Ersted, of Copenhagen, in 
1819, first made known the law of electro-magnetic attrac- 
tion and repulsion ; since which, the progress of this branch 
of science has been very rapid. 

§ 166. GalvarwscopeSf or Galvanometers, are instruments 
by which we measure the force and direction of a galvanic 
or voltaic current, which is often a most 
important thing to be known. The prin- 
ciple of the last arrangement is here ap- 
plied. In order to free the magnetic 
needle from the directive tendency which 
it receives from the earth's magnetism, 
two needles are used, with their unlike 
poles placed opposite to each other, (see 
fig. a,) one within and the other above 
the coil. They will then hang suspend- 
ed by the silk fibre which supports them, 

What is the effect of the needle? If the wire is bent into a rectangle, 
what is the effect? Who discovered the first law of electro-magnetism, 
andwheii? §166. What are galvanoscopcs ? 



118 



ELECTRICITY. 



with no tendency of their own to swing in any direction, 
since they are wholly occupied with their own attractions 
and repulsions, and their directive power is neutralized; 
consequently, they are free to move 
with the slightest influence of any cur- 
rent passing through the coil, however 
feeble. Such an arrangement is called 
an astatic needle. * To give it greater 
delicacy, and prevent the currents of 
air from moving it, a glass shade (fig. 
h) is placed over it, and the move- 
ments of the needle are read on the 
graduated circle. | For the purpose 
of elementary explanation of the prin- 
ciples of electro-magnetism, such a 
needle as that figured in the last sec- 
tion will answer. The tendency of 
the galvanometer-needle, it will be re- 
membered, is always to place itself at right angles to the 
direction of the electrical current, that position being the 
equator of the attracting and repelling powers, and conse- 
quently a point of equilibrium. 

§ 167. Ampere's Theory. — The discovery of the first law 
of electro-magnetic influence by (Ersted, attracted great at- 
tention ; and in 1820, M. Ampere, a French philosopher, 
made the suggestion that the magnetism of the earth was duo 
to the influence of the sun's rays, which, falling on the 
earth, might be considered as encircling it in an unending 
series of spiral lines, producing in it the phenomena of mag- 
netic induction, (§ 140.) The discovery, by (Ersted, of the 
magnetic influence of an electric current, (§ 165,) led him to 
conjecture, that if such a current was made to pass in a spiral 
about any conductor, it would become magnetic. This idea 
led to the discovery of the phenomena of the 

§ 168. Helix.X — A wire coiled in the form here repre- 




Explain the figures, 
pere's theory. 



What is an astatic needle? § 167. State Am- 



* From the Greek, astaios, just balanced. 

t It was a galvanometer such as this which was referred to as being 
used in Melloni's apparatus, (§ 104.) 

X So called from the Greek, helisso, to twist round ; Latin, heliXf m 
allusion to the coiling of a vine about a tree. 



ELECTRO-MAGNETISM. 



119 




sented, and made the medium of communication for a vol- 
taic current, becomes capable 
of manifesting very strong mag- 
netic influence on any conduc- 
tor placed in its axis. A deli- 
cate steel needle, laid in the 
helix, will be drawn to the cen- 
tre and held suspended there, without material support, like 
Mahomet's fabled coffin. If the needle be of steel, the mag- 
netism it thus receives is retained by it ; but if it is of soft 
iron-, it is a magnet only while the current is passing ; brass, 
lead, copper, or any other metallic conductor, can in this 
way be made to manifest temporary magnetic power. The 
more closely the helix is wound, and the more revolutions 
it makes, the more powerful is the magnetism which it can 
induce, (§ 165.) It is essential that the wire of which it is 
formed should be insulated from contact with itself, by be- 
ing wound with silk or cotton, or coiled in an open spiral, 
as in the figure. A short and stout wire of lead or copper, 
connecting the poles of a single cylinder battery, when ex- 
cited, becomes strongly magnetic, as may be seen by the 
bundle of iion-filings which it will then attract ; each filing 
becomes itself a magnet, and the whole surround the wire 
in a beautiful tuft or festoon of spiral lines. The moment 
the connection between the poles is broken, they all fall, 
and the wire has not power to lift a single particle of iron. 

^ 169. De La Rives^ Ring. — We infer, therefore, that the 
helix itself has polarity, and this is beautifully proved by the 






arrangement represented in the an- 
nexed figure, called De La Rives' 
ring, which is simply a small wire 
helix, whose ends are attached to the 
little battery of zinc and copper con- 
tained in a glass tube, and the whole 
made to float on the surface of a 
basin of water, by means of a large 
cork, through which the glass tube is thrust. On exciting 
this small battery by a little dilute acid, poured into the 




§ 168. What discovery did Ampere's theory lead to ? What is a lielix, 
and its action ? How does a stout wire in the poles of a battery sliow the 
spiral or tangential direction of the current? § 169. What does De La 
Rives' ring show ? Explain it. 



120 



ELECTRICITY. 



tube, and placing the apparatus on the water, it will at once 
assume d^ polar direction, as if it were a compass-needle, 
the axis of the helix being in the magnetic meridian ; and 
it will then obey the influence of any other magnet brought 
near it, manifesting the ordinary attractions and repulsions. 
170. Electro-magnets. — It is obvious we may avail our- 
selves of the principle of the helix to manufacture artificial 
magnets ; if steel wires are introduced, as before stated, 
(^ 168,) within the helix, they become permanent magnets, 
while soft iron is made only temporarily so. The position 
of the poles may be determined by a little reflection from 
what has been already said. If the helix is wound from 
left to right, the poles will be the reverse of their position ; 
if the winding was from right to left, a reversal of the direc- 
tion of winding will be the same as changing the poles. By 
reversing the winding in the middle of the helix, we shall 
establish two sets of poles ; and if it is twice reversed, 
three sets will be produced, and so on; we can also re- 
verse the polarity of our magnets at will, by changing it end 
for end in the helix, or by reversing the di- 
rection of the current. Obvious as was the 
conclusion to which these principles lead, 
Prof. Henry, of Princeton, was the first 
who attempted to apply them to the produc- 
tion of large magnets, from soft iron wound 
with covered wire, as in the figure. In 
this way, he succeeded in producing the 
most powerful magnets which have been 
made. One on his plan, now in the La- 
boratory of Yale College, has lifted 2500 
■" pounds. In these magnets the wire is in- 
sulated, and wound in short coils of 60 to 
100 feet, the opposite ends of which are, of 
course, connected with the opposite poles of 
A small battery was used in one of his exper- 
iments, consisting of two concentric cylinders of copper 
soldered into a cup, to hold half a pint of dilute acid, with 
a zinc cylinder immersed in it. With this, 650 pounds 
were sustained by the magnetism induced in a bar of soft 




the battery. 



§ 170. How is the principle of the helix applied to making artificial 
magnets? If the helix is reversed? If twice reversed ? Mention Prof. 
Henry's magnets. How much have they been made to lift ? 



ELECTRO-MAGNETISIVr. 



121 



must remember 
from the voltaic 



iron, two inches square, twenty inches long, and bent into 
the horse-shoe form. This was wound with 540 feet of 
insulated copper bell-wire, in nine separate coils of 60 feet 
each. With a larger battery, the same magnet sustained 
750 pounds. A very small electro-magnet has been made to 
lift 420 times its own weight. 

§171. The Magic Circle. — The learner 
that the magnetism of soft iron, induced 
current, is not the result of contact between 
the helix or coil and the iron ; but this effect 
is produced through an intervening space 
of air, or other material which is non-con- 
ducting to ordinary electricity, or galvan- 
ism. The annexed figure shows two small 
semicircles of soft iron, forminor a rinor 
when united, and fitted with handles ; a 
small coil of insulated wire, (R,) placed 
within the soft iron circle, will cause the 
induction of magnetism in it, the moment 
the terminal wires (a b) are connected 
with a small battery. The rings of iron 
and of wire are quite distinct and may be 
moved about in each other ; the soft iron 
semicircles &eem bound together as if by 
magic, and hence the apparatus has been 
called the magic circle. Fifty or sixty 
pounds are easily sustained by such an 
apparatus, made, of iron about half an inch 
in diameter. 

§ 172. Electro-magnetic Motions. — The great power of 
magnetism induced in soft iron, early suggested its applica- 
tion to the moving of machinery. As yet, however, we have 
produced nothing which can at all take the place of steam 
or water, as a moving power. The causes of failure can- 
not well be explained in this place, as they involve some 
chemical reasoning which would be in anticipation of our 
knowledge. 

Faraday was the first who succeeded in producing mo- 
tion by the mutual action of magnets and conductors. It is 




§ 171. Is electro-magnetism the result of contact ? Illustrate this from 
the magic circle. § 172. Has the great power of electro-magnets been 
made available for use? Who first produced electro -magnetic motion? 

11 



122 



ELECTRICITY. 



quite impossible to name, much less describe, even a tenth 
part of the ingenious and instructive forms of apparatus 
which have been contrived by various experimenters for 
producing motion. 

Ainpere's Rotating Battery is an instructive form of appara- 
tus, and one of the lirst contrived. 
In this, a small double cylinder or cup 
of copper is hung by a pivot over and 
around the pole of a U magnet, 
standing as represented in the figure. 
This holds the dilute acid, into which 
the zinc cylinder (Z) dips, whichis sus- 
pended on another pivot so as to hang 
freely. As soon as the acid water is 
poured into the cup, a current of elec- 
tricity will flow (§ 160) from the zinc 
to the copper, over the wire and 
through the pivot to the zinc again. 
The zinc and copper are in the con- 
dition of two conductors, conveying 
an electric current in opposite direc- 
tions, and being under the influence 
of the poles of the magnet, (§ 165,) and 
free to move, they revolve in opposite 
directions. If each pole is thus provided, the cups and zincs 
on each will revolve difl*erently. 

§ 173. Pagers Revolving Armature!^ — One of the simplest 
forms of the electro-magnetic engine is that figured on the ne:jkt 
page, in which an electro-magnet (M) is fixed on a stand, with 
its poles in an upright position. A brass wheel is so pla- 
ced over it, that three bars or armatures of soft iron, (A,) 
which divide the circumference, may pass very near to the 
poles of the magnet, as the wheel turns. The arrangement 
is such, that the revolution of the wheel shall break the 




Describe Ampere's rotating battery, 
armature, and how does it operate ? 



§ 173. What is Page's revolving 



* Dr. C. G. Page of the Patent Office, Washington, is the author of 
numerous new and beautiful electro-magnetic machines, [for an account 
of which see the American Journal of Science, passim,] and is one of the 
most successful cultivators of this science. His apparatus, with much 
other useful matter, will be found described and figured in a useful little 
work called Davis's Manual of Magnetism, 18mo Boston, 1842. Sev- 
eral of the figures here given are from Mr. Davis's work. 



ELECTRO-MAGNETISM. 



123 



connection between the battery and the electro-inagnet, 
three times in every revolution. This is accomplished by 
the wire (B) which plays upon three 
pins of wire, in the little disc seen 
upon the horizontal axis of the 
wheel. As often as these pins 
touch the wire, (B,) so often the 
circuit is completed; and the soft 
iron (M) becomes a magnet. As 
soon, however, as this contact is 
broken, M ceases to be a magnet. 
Now this happens three times in 
every revolution of the wheel, and 
the breaking of contact is so con- 
trived that it always happens just 
when one of the soft iron armatures 
(A) comes over the poles of the 
electro-magnet. The bars (A) 
being each in succession strongly 
attracted to the poles of the magnet, 
cause the wheel to move, and the 
revolution, being once established, 
is kept up with great velocity. If 
the magnetism in M was not de- 
stroyed by the contact-breaker, (B,) at the very time whea 
A comes over the poles, the revolution would be arrested 
by the strong attraction of the magnet for the armature. 

§ 174. Henry^^s Coils. — When an electrical <;urrent from 
a single pair of plates is passed through a long conductor, 
as a spiral of copper ribbon, or a long bell-wire, it will be 
found, at the moment of breaking the contact between the 
conductor and the battery, that vivid sparks will appear, and 
a feeble shock will be felt if the moistened fingers grasp 
the naked conductors. 

A long conductor then supplies the place of an increas- 
ed number of plates in a voltaic series, and to some degree 
imparts the quality of intensity (^ 162) to a current of quan- 
tity. A flat spiral of copper ribbon one hundred feet long, 
wound with cotton, and varnished, shows these effects well. 
A magnetic needle will be powerfully aflected by this coil 
while the current is passing ; the N. or S. pole being drawn 




§ 174. What is the eifect of Henry's coils on the voltaic curreuti 



124 



ELECTRICITY. 




toward the centre, (see the figure,) according to the direc- 
tion of the current, the reversal 
of the current producing a rever- 
sal in the direction of the needle. 
The opposite sides of the spiral 
of course produce opposite effects 
on the needle. Its axis, it will be 
seen, is the same as that of the 
helix, (§ 168,) and will in like 
manner produce magnetism. The 
magnetism is, however, to be dis- 
tinguished from the new effects excited by the passage of 
the feeble current through the coiled conductor, on break- 
ing contact, i. e., the vivid spark and the shock. The latter 
is feeble with 100 feet of copper ribbon, and becomes more 
intense (§ 177) if the length of the conductor be increas- 
ed, the battery remaining the same ; but the sparks are dimin- 
ished by lengthening the conductor. The increase of in- 
tensity in the shock is, however, limited by the increased 
resistance or diminished conduction of the wire, which finally 
counteracts the influence of the increasing length of the 
current. On the other hand, if the battery power be in- 
creased, the coil remaining the same, these actions diminish. 
This class of phenomena has been attributed to the induc- 
tion of a current upon itself. Prof. Henry first observed 
the effects here described, and has made an extended series 
of researches on this species of induction, as well as that 
mentioned in the next section. 

§ 175. Secondary Cwrre?i^6".— If a long coil of fine insulated 
wire be brought within a small distance of the flat spiral, fig- 
ured in the last section, a new species of induction will be de- 
tected in the coil of fine wire. The arrangement used by Prof. 
Henry is seen in the annexed figure. A small sustaining 
lattery (L) is connected with the flat spiral of copper rib- 
bon, (A,) by wires from the battery cups, (Z and C.) This 
communication is broken at will, by drawing the end of 
one of the battery wires (Z) over the rasp on the spiral. 
When the coil of fine wire (W) is in the position indicated 



What does the long conductor imitate? How is the magnetic needle 
affected by the flat spiral ? How are the two efiects of shock and spark 
related to the length of the conductor? To what does Prof. Henry at- 
tribute these effects? § 175. What are secondary currents ? Explain 
the arrangement here figured, and the effects. 



electro-magnetism:. 



125 



in the figure, and the hands grasp the conductors at the ex- 
tremities, a violent shock is felt by the person holding the 




conductors, as often as the circuit is broken by the passage 
of the wire over the rasp. When the coil ( \V) contains sev- 
eral thousand feet of wire, the shocks are too intense to be 
borne. As this induction takes place through an interven- 
ing space of air, or non-conductors, v^e can, by placing the 
spiral (A) against a division wall or the door of a room, give 
shocks to a person in another room, who grasps the con- 
ductors of the wire coil, (W,) and brings it near to the wall 
on the side opposite to A. This pleasing effect is produced 
as if by magic, without a visible cause. A screen or disc 
of metal introduced between the two coils will cut off this 
inductive influence, by itself becoming the medium of an in- 
creased current. But if it be slit by a cut from 
the centre to the circumference, as a h in the ' 
figure, the induction of an intense current in W 
is the same as if no screen were present. Discs or screens 
of wood, glass, .paper, or other non-conductors, offer no im- 
pediment to this induction. 

§ 176. Induced currents of the thirds fourth, and fifth 
order. — If the wires from W be connected with another flat 
spiral, and it with a second coil of fine wire, and so on, a 
series of currents will be induced in each alternation of coils. 
The secondary intense current in B, will induce a quantity 
current in the second flat spiral, (C ;) and a second fine w-ire 
coil (W) will induce a tertiary intense current, and so on. 
These currents have been carried to the ninth order, de- 
creasing each time in energy by every removal from the 



When is the shock felt by the person holding the ends of the fine wire ? 
What magical modification of the experiment is mentioned ? How do 
screens of metal affect the induction? How, if they are slit? How, if 
of non-conducting substances ? 

11* 



I 



12G ELECTRICITY. 

original battery current. The polarity, or direction of these 




secondary currents alternates, commencing with the secon- 
dary. Thus the current of the battery is 4- ; and the sec- 
ondary current is + ; the current of the third order is — ; 
the current of the fourth order is + ; and the current of the 
fifth order is — . These alternations are marked in the 
figure above. 

§ 177. Compound Electro-magnetic Machines. — Dr. Page 

and Mr. Davis, by 
combining and mod- 
ifying the results 
just briefly enumer- 
ated, have produced 
a great number of 
original and beautiful 
machines, founded 
on the principle of 
the flat spiral, secon- 
dary intense currents, and induced magnetism. One of 
these, contrived by Dr. Page, is figured in the margin. 

In this little machine, a short coil of stout insulated cop- 
per wire forms a helix, within which some straight soft 
iron wires (M) are placed. The battery current is made 
to pass through this stout wire, by which means magnetism is 
induced (§168) in the soft iron. The conducting wires 
are so arranged beneath the board, that the glass cup (C) 
containing some mercury is in connection with the battery. 
The bent wire (W) dips into this mercury, and also by a 




§ 176. Explain the induced currents of the third, fourth, and fifth or- 
der, and their several polarities. § 177. How are the principles of § 174 
and § 175 combined in the instrument here figured? Where is the mag- 
netism? 



ELECTRO-MAGNETISM. 127 

branch into B, and when in the position shown in the figure, 
the current from the battery will flow uninterruptedly. As 
soon, however, as the battery connection is completed, M 
becomes strongly magnetic, and draws to itself a small ball 
of iron on the end of P, this moves the whole wire (P W) 
and raises the point out of the mercury, (C ;) as the wire 
leaves the mercury, a brilliant spark is seen on its surface, 
(^ 175 ;) the contact being thus broken with the battery, M 
ceases to receive induced magnetism, and the ball (P) being 
consequently no longer attracted to M, the wire (W) falls by 
gravity to its position in the figure. This again establishes 
the battery connection, and the same effects just described 
recur ; thus the bent wire (W) receives a vibratory motion, 
and at each vibration, a brilliant spark is seen at C, and M 
becomes magnetic. It remains only to mention that the 
short quantity wire is surrounded by a fine intensity wire, 
2000 to 3000 feet long, having no metallic connection with 
the battery or quantity wire, and whose ends terminate in two 
binding screws on the left of the board. The fine w^ire re- 
ceives a secondary induced current like the coil, (W, § 175,) 
which, if touched, produces the most intense shocks at each 
vibration of the wire. This beautiful and instructive ma- 
chine is the type of many others contrived upon the same 
principles, which are manufactured by Mr. Davis, and fig- 
ured in his '' Manual of Magnetism."* 

^ 178. The Electro-magnetic telegraphic one of the many 
beautiful applications of scientific principles to the purposes 
of society, in which our age abounds. That employed in 
this country! is the ingenious invention of Prof. S. F. B. 
Morse, and is remarkable for its simplicity and success. 

The operation of the telegraph depends on the fact, that 
we can make an electro-magnet at any point, no matter how 
distant from us, provided a good metallic communication can 

Where is the spark? and where the shocks? §178. On what does 
the operation of the telegraph depend ? Illustrate this. 

* The instrument called Separable Helices, (figure 108, of his book,) 
is a very instructive form of the same apparatus, in which the coils are 
separable. 

t In England an ingenious instrument of Prof. Wheatstone, is used, 
and several others are employed in different countries of Europe. They 
are all, however, considered as inferior in simplicity and efficiency to 
Morse's. 



128 



ELECTRICITY. 



be made, by conducting wires between the battery and the 
distant station. We have no difficuhy in understanding 
how the power of the battery on our table may, by long 
wires, be made to move any electro-magnetic machine on 
the other side of our room, or in an adjoining apartment. 
We have only to extend this idea to places distant from each 
other, 100, or lOOO, or 10,000 miles, and we have a con- 
ception of the magnetic telegraph. The machinery re- 
quired is of the simplest kind. In the accompanying figure 




we have a view of its most essential parts. A simple elec- 
tro-magnet, [m 771,) with its poles upward, receives its induced 
magnetism (^ 170) from a current of electricity conducted 
by the wires (W W) from the distant station. Suppose that 
the battery which excites this current is in Washington, and 
the electro-magnet is in Boston. As soon as the circuit is 
completed by the union of the poles in Washington, m m 
become magnets, and draw to their poles an armature of soft 
iron (a) on the lever, (l.) The motion of this lever starts a 
spring which sets in motion the clock arrangement, (c.) 
This clock machinery, in consequence of the weight attached 
to it, will, when once set in motion, continue to move. As 
soon as it begins to move, the bell [h) is rung by the machine- 
ry, to warn the superintendent that he is about to receive a 
communication. The immediate object of the clock machinery 



Explain the apparatus as here figured? What is the object of the 
clock-work? 



ELECTRO-MAGNETISM. 129 

is to draw forward a narrow ribbon of paper, (p, p,) in the 
direction of the arrows, and to cause it to advance with a 
regular motion. This paper passes by the end of the pen 
lever, (/,) in which is a steel point, (^,) that indents the 
paper. U m m were constantly magnetized, the mark 
made by the point (s) would be a continuous line. But we 
have before seen that we can make and discharge an elec- 
tro-magnet as often and as fast as we please ; the instant, 
therefore, the circuit (w w) is broken by the operator at the 
battery in Washington, m m ceases to be a magnet, and 
lets go the iron armature, (a,) when the point (s) of the lever 
falls, so as no longer to mark the paper. The circuit being 
again renewed, the point marks again ; and this may be ac- 
complished as often as the operator at Washington pleases. 
The length of time that the circuit is closed, will be exactly 
registered in the corresponding length of the mark made by 
s. Now the breaking of the circuit is performed by touch- 
ing a spring. A touch will produce a dot, a continued press- 
ure a long line, and intermitting repeated touches a series 
of dots and short lines. This enables the operator to mark 
the paper at Boston with a series of dots and lines, so ar- 
ranged as to form a telegraphic alphabet, by means of which 
he can easily and rapidly communicate his thoughts. To 
complete tha arrangement, the man in Boston must have his 
own battery in connection with another register, like the 
figure, in Washington. In practice only one wire is used 
with each register, the circuit being completed by connect- 
ing the other pole of the battery with the moist earth by 
means of a buried metallic plate and a wire. Such is a brief 
account of one of the most important and remarkable discov- 
eries of modern times ; many particulars are purposely 
omitted, to avoid confusion in the main idea. The paper 
ribbon (p) is supplied from a large coil not shown in the 
figure. If it were possible to unite the antipodes by tele- 
graphic wires, no measurable time would be required to make 
communications, such is the inconceivable rapidity of elec- 
trical currents. 

One curious fact connected with the operation of the tele- 
graph, is the induction of atmospheric electricity upon the 

How does the point mark the paper? What relation is there between 
the length of the marks and the battery circuit ? How are the con- 
ducting wires arranged? What is said of the atmospheric electricity? 



130 



ELECTRICITY. 



wires to such an extent, as often to cause the machines at 
the several stations, to record the approach of a thunder- 
storm. 

§ 179. Magneto-Electricity. — As we have seen effects 
produced from galvanism, which exactly resemble those of 
ordinary machine electricity, and the magnetic influence, so, 
conversely, we might expect the production of electrical 
effects from the magnet. This class of phenomena was 
discovered by Faraday in 1831, and our countryman, Mr. 
Saxton, soon contrived a machine very similar to the one of 
which a figure is here given, called a Magneto-electrical 




Machine ; which consists of a powerful magnet, (S,) secured 
to a board, with its poles so situated that an " armature," 
formed of two large bundles of insulated copper wire, (W,) 
wound on soft iron axes, may be revolved on an axis before 
the poles, by the multiplying wheel, (M.) A current of elec- 
tricity is thus induced in W, just as in the flat coils, the per- 
manent magnet (S) taking the place of the flat spiral, (W,) 
(§ 175.) The current excited in W is led off by conductors 
to the screws, [p and ??.,) the continuity of the current being- 
broken (in imitation of the rasp in ^ 175) by a con- 
trivance at h on the axis, called a break-piece, which 
is made by alternate ribs of metal (c) and ivory [i) as 
in the annexed figure ; the current is broken by the 




§ 179. What is magneto-electricity? Who discovered this class of 
phenomena, and when ? Explain Saxton's machine. Explain the rela- 
tions of the quantity and intensity wire to the simila.r eiFects of the vol- 
taic battery. 



THERMO-ELECTRICITY. 



131 



ivory and renewed by the metal, and at every break the per- 
son whose hands grasp the conductors secured to p and n - 
feels a sharp shock, which may be graduated at will by the 
rapidity of the revolutions of M, and by the adjustment of 
the break, {b.) A long and fine wire — say 3000 feet of 
wire -^Q of an inch through — is required to produce shocks 
and chemical decompositions. A shorter and stouter wire, 
as 250 feet of w^ire -^-^ or -^-^ inch in diameter, will produce 
no shock, but will deflagrate the metals powerfully, and 
produce a secondary current of induction in soft iron. We 
thus imitate in magnetism the effects produced from a vol- 
taic current, (§ 162 ;) the short and stout wire of the armature 
is the simple circuit of large plates ; the long and fine wire is 
like the compound circuit of smaller plates. 

5. Thermo-Electricify^ or the Electrical Current excited hy 

Heat. 

§ 180. If two metals unlike in crystalline structure and con- 
ducting power be united by solder, and the point 
of their union be heated or cooled, an electrical 
current is excited, which will flow from that 
point to the metal which is the poorest conduc- 
tor. Bismuth and antimony are such metals, 
(bad conductors,) and unlike in crystalline struc- 
ture. If two bars of these metals be united, 
as in the figure, and the point [e) be warmed 
by a lamp, a current will be set in motion which will flow 
from h to a, as in the figure. The 
compass needle may be thus affected, 
as by the voltaic current, (^ 165.) 
For this purpose two bars may be 
mounted as in the figure, and their 
junction being heated by a lamp, the 
needle will swing. When several 
such are joined, we have a greatly increased effect, as will 
be remembered in the thermo-electric pile in Melloni's ap- 
paratus, (§ 104.) 





§ 180. What is thermo-electricity? In what substances is it excited? 
What metals are here named ? Which way does the current flow ? 



132 CHEMICAL PHILOSPHY. 



PART IL— CHEMICAL PHILOSOPHY. 

I. ELEMENTS AND THEIR LAWS OF COMBINATION. 

§ 181. Number and Classification of Elements,— -^q 
have already defined the chemical sense of the word 
Element, (^ 14,) and mentioned that there were fifty-six 
such substances at present known to us. There are also 
three or four other substances which have been lately 
proposed as elements of the metallic class, about which, 
however, we know so little, that they are not included in 
the following list. Thus, the substance known as Yttria has 
been shown by Mosander to be a mixture of the oxyds of 
three metals, Yttrium, Erbium, and Terbimn. Rose, in like 
manner, has determined the existence of two new metals, 
Pelopium and Niobium, in the Columbite ; and Svanberg 
has demonstrated the existence of still another element, 
Norium, in the Zircon. , 

Of the fifty-six elementary substances which are em- 
braced in this table, about forty belong to the class of 
metals, and the remainder are considered as non-metallic. 
This distinction, which is extremely convenient, is not 
quite correct ; since there are some substances which 
seem to possess an intermediate character. Of the whole 
number of elements, fourteen constitute the greater part 
of our earth, its atmosphere and waters. The remainder 
are comparatively rare, and we shall not be able to give 
much useful information about them in this work. The 
same laws of combination apply to the whole, and we shall 
therefore best promote the objects of this work by dwelling 
on the first principles of Chemical Philosophy, and illus- 
trating them by a selection of facts, rather than by attempt- 
ing the task of giving too much detail. The names of the 
elements are as follow : 

(1.) No a- Metallic Elements. — Oxygen, Chlorine, Bromine, 
Iodine, Fluorine, Sulphur, Selenium, Phosphorus, Nitrogen, 
Carbon, Silicon, Boron, Hydrogen, (13.) 

§181. How many elements do we know? How are these divided? 
Name the non-metallic elements. Also the metallic. 



COMBINATION BY WEIGHT. 133 

(2.) Metallic Elements, — Potassium, Sodium, Lithium, 
Barium, Strontium, Calcium, Magnesium, Aluminium, Glu- 
cinum, Yttrium, Zirconium, Thorium, Manganese, Iron, 
Nickel, Cobalt, Zinc, Cadmium, Bismuth, Uranium, Copper, 
Lead, Cerium, Lantanum, Didymium, Chromium, Tin, 
Tungsten, Molybdenum, Vanadium, Columbium, (or Tanta- 
lum,) Titanium, Antimony, Tellurium, Arsenic, Silver, Gold, 
Mercury, Platinum, Palladium, Rhodium, Iridium, Osmium, 
(43.) 

§ 182. State in which the elements exist. — At common 
temperatures, and when set free from combination, nearly 
all the elements are solids. Two are fluids, (Mercury and 
Bromine,) and five are gases, namely. Chlorine, Fluorine, 
Hydrogen, Oxygen, and Nitrogen. The remarks on the three 
states of matter, (^ 16,) will be here recalled. A few only of 
the elements are naturally found in a free or uncombined 
state, among which we may name Oxygen, Mitrogen, 
Carbon, Sulphur, and nine or ten metals. All the rest are 
locked up in fixed combinations with each other, and so 
completely concealed or disguised as to be known only to 
the chemist. 

1. Combination hy Weight. 

§ 183. The laws by which the elements associate to- 
gether to form compomids, are included in the four following 
propositions. 

1st LAW. A compound of two or more eleme7its is 
always formed hy the union of certain definite and unalterable 
proportions of its constituent elements. 

This is the law of " definite proportions.^^ 

2d LAW. When two bodies unite in more proportions 
than one, these proportions hear some simple relation to each 
other. 

This is the law of " multiple proportions.^^ 

3d LAW. When a body (a) unites with other bodies, (b, 
c, D, Sfc.,) the proportions in which b, c, and d, unite with a. 



§ 182. In what state do the elements exist ? Which are fluids ? Which 
are gases? Which are free or uncombined? In what state are the 
others ? § 183. State the first law of combination ? What is this law 
called? What is the second law ? What is this law called? What is 
the third law, and what called? The fourth, and what called :' What 
is said of these laws ? 

12 



134 ELEMENTS AND THEIR LAWS OF COMBINATION'. 

will represent in numbers the proportions in which they will 
unite among themselves, in case such union takes place. 
This is the law of " equivalent proportions,''^ 
4th LAW. The combining proportion of a compound body 
is the su7n of the combining weights of its several elements. 
This is the law of the " combining numbers of compounds.^'' 
These four laws are the foundation of all chemical 
science, and should receive the attention which their great 
importance demands. We will briefly illustrate their 
meaning, which will be done, however, more effectually by 
the constant use we shall have to make of them, on almost 
every succeeding page in the elementary chemistry. 

^ 184. Definite Proportions. — Analysis (§ 59, note) has 
shown us that a given compound is always formed of cer- 
tain elements in definite proportions ; and that no change can 
take place in the number or proportion of its constituent 
elements, without destroying its peculiar character, and 
forming a new substance. Thus, in nine grains of water 
there are eight grains of oxygen and one grain of hydrogen. 
Any attempt to form water from any other proportion of its 
elements would be useless. Constancy of composition is 
essential to the being of all chemical compounds. 

^ 185. Multiple Proportions. — If a body (A) unite with a 
body (B) in more proportions than one, thus producing more 
than one compound of the two elements, these proportions 
bear a simple relation to each other. (1.) We may have a 
series of compounds represented by the expressions, A + B : 
A+2B : A+3B : A+4B : A-1-5B: in which one, two, 
three, four, and five, parts by weight of B, unite with one 
part of A, forming five separate and distinct compounds. 
Farther on we shall find that the elements oxygen and 
nitrogen unite in this manner, forming five distinct com- 
pound bodies, precisely in the manner here represented; 
among which are the well known substances, nitric acid, 
and the exhilarating or laughing gas. (2.) In place of the 
simple ratio of numbers here explained, we may have 
another series of compound bodies, whose elements bear to 
each other an intermediate ratio. Thus the expressions, 
2A + 3 B : 2A+5 B : 2A + 7B : represent a series of com- 

§ 184. What has analysis shown? Illustrate this. § 185. tllnstrate 
the law of multiple proportions. 



COMBINATION BY WEIGHT. 135 

pounds, of which our future studies will afford us several ex- 
amples. The several compounds formed by the union of 
arsenic and oxygen have this relation of the elements. 

^ 186. Equivalent Proportions.— Thi^ may be considered 
as the most important law in chemical philosophy, and its 
discovery and application have been the great cause of the 
rapid advance of modern chemistry. Chemical analysis has 
shown that the body, oxygen, can form one definite compound, 
or more than one, with every other element yet discovered, 
except, perhaps, fluorine. The compounds of oxygen with 
the elements being perfectly definite, (^ 182,) can all be ex- 
pressed in numbers, which numbers will truly express the 
combining weights of the several bodies. For the sake of 
illustration, let us assume that it requires eight parts by 
weight of oxygen to unite with each of the other elements, 
and that these eight parts require various weights of the 
several elements. Then we can make a table which shall 
correctly express these numerical relations. 

' 6 parts of carbon. 

1 part of hydrogen. 

35*41 parts of chlorine. 

108-12 of silver. 

2714 of iron. 

101-27 of rnercnry. 
^16-09 of sulphur. 

And we might go on thus through the whole list of ele- 
mentary substances, analyzing their several compounds with 
oxygen, and setting down the combining numbers of each 
in one table. Tbe few examples given above are, however, 
suflicient for our purpose. The selection of oxygen, and of the 
number 8 affixed to it, as a standard of comparison for the 
other bodies, is entirely arbitrary, and not from any peculiar 
relation which this element sustains to the others, which is 
not common to the whole list of elements, except that it 
enters into combination more generally than any other ele- 
ment. But selecting oxygen 8, as a starting point, all the 
other numbers expressing the combining weight of each ele- 
ment have been determined with the greatest care by often- 
repeated analyses. Let it be understood then, that if any 
of the bodies in the table should form compounds with each 

§ 186. Illustrate the law of equivalent proportions What is said of 
oxygen ? What is assumed for ilkistration ? How do other bodies stand 
related to oxygen ? How has this been determined ? 



Thus, 8 parts of oxygen unite with 



136 ELEMENTS AND THEIR LAWS OF COMBINATION. 

Other, the weights in which they will unite will be in the 
exact proportion of the numbers severally affixed to them. 
Thus, if hydrogen unites with chlorine to form a new com- 
pound, {hydro-chloric acid,) it will require one part of hydro- 
gen to 35-41 parts of chlorine to form such compound. One 
pound of hydrogen will unite to 35-41 pounds of chlorine, 
and will form 36-41 pounds of the compound. Any ex- 
cess or deficiency of either of the elements will make no 
difference with the result, and the above law will in all cases 
be found strictly true. If sulphur and mercury unite to 
form a third body, it will be only in the proportion of the 
numbers 1609 and 101*27 ; and if sulphur unite with iron, 
it will be as 1609: 27-14. 

We see then that the several numbers are truly the equiv- 
alents o( each other, as they are all the equivalent of oxygen, 
and are, therefore, most appropriately called " equivalent 
proportions,^^ or " equivalent numbers. " 

§ 187. Table of Chemical Equivalents. — In the following 
table, the equivalent or combining numbers of all the ele- 
mentary bodies are given in accordance with the latest and 
best authorities. Two columns of combining proportions 
are given ; in the first, hydrogen, and in the second, oxygen, 
is used as the unit of comparison. Because hydrogen 
enters into combination with other bodies, in a smaller 
weight than any other known element, it has generally been 
used in Great Britain and in this country as the basis of the 
scale of equivalent numbers. It was also believed, and is 
still, by some good chemists, that the numbers expressing 
the combining weights of all bodies would be found, on 
more accurate research, to be simple multiples of the unit 
hydrogen. If this view were correct, it would give us the 
great convenience of avoiding fractional numbers. But the 
most rigid experiments have failed to prove this idea to be 
true, and as it has no necessary foundation in the nature of 
things, we are not at liberty to adopt it. Berzelius and 
most European chemists consider oxygen as 100; and the 
second column of figures in the table gives the equivalents 
according to this scale. 



Illustrate this in the case of hydro-chloric acid. If there is an excess or 
deficiency of either element, what then ? What term seems most appro- 
priate then, to express this? §187. What does the table show us ? 
What is said of the hydrogen scale, and why has it been used ? 



COMBINATION BY WEIGHT. 



137 



Table of elementary substances, with their equivalents and 

SYMBOLS,* 







H.==l, 








H.=l, 






Sym- 


or 






Sym- 


or 






bol, t 


Oxy.=8. 


Oxy.=100 




bol. 


0xv.=8. 


Oxy.=100. 


Aluminium, 


Al 


13-69 


171-17 


Manganese, 


Mn 


27-67 


345-89 


Antimony, 


Sb(l) 


129-04 


1612-90 


Mercury, 


Hg(6) 


101-26 


1265-82 


Arsenic, 


As 


75-2] 


94008 


Molybdenum, 


Mo 


47-88 


598-52 


Barium, 


Ba 


68-55 


856-88 


Nickel, 


Ni 


29-59 


369-68 


Bismuth, 


Bi 


70-95 


886-97 


Nitrogen, . 


N 


14-06 


175-75 


Boron, 


B 


10-90 


136-20 


Osmium, 


Os 


99-56 


1244-49 


Bromine, 


Br 


78-26 


978-31 


Oxygen, 





8- 


100- 


Cadmium, 


Cd 


55-74 


696-77 


Palladium, 


Pd 


53-27 


665-90 


Calcium, 


Ca 


20- 


250- 


Phosphorus, 


P 


31-38 


392-28 


Carbon, 


C 


6- 


75- 


Platinum, 


PI 


98-68 


1233-50 


Cerium, 


Ce 


45-98 


574-70 


Potassium, 


K(7) 


39-19 


489-92 


Chlorine, 


CI 


3541 


442-65 


Rhodium, 


R 


52-11 


651-39 


Chromium, 


Cr 


28-14 


351-82 


Selenium, 


Se 


39-57 


494-58 


Cobalt, 


Co 


29-52 


368-99 


Silicon, 


Si 


22-18 


277-31 


Columbium, 


Cm 


184-59 


2307-43 


Silver, 


Ag(8) 


108-12 


1351-61 


Copper, 


Cu(2) 


31-65 


395-70 


Sodium, 


Na (9) 


2327 


290-90 


Didymium, 


Di 






Strontium, 


Sr 


4378 


547-29 


Fluorine, 


F 


18-70 


233-80 


Sulphur, 


S 


1609 


201-17 


Glucinum, 


G 


26-50 


331-26 


Tellurium, 


Te 


64 14 


801-76 


Gold, 


Au(3) 


99-44 


1243- 


Thorium, 


Th 


59-59 


744-90 


Hydrogen, 


H 


1- 


12-5 


Tin, 


Sn (10) 


58-82 


735-29 


Iodine, 


I 


126 36 


1579-50 


Titanium, 


Ti 


24-29 


303-69 


Iridium, 


Ir 


98-68 


1233-50 


Tungsten, 


W(ll) 


94-64 


1183- 


Iron, 


Fe(4) 


2714 


33921 


Vanadium, 


V 


68-55 


856-89 


Lantanum, 


Ln 






Uranium, 


u 


60- 


750- 


Lead, 


Pb (5) 


103.56 


1294-50 


Yttrium, 


Y 


32 20 


402-51 


Lithium, 


L 


6-43 


80-33 


Zinc, 


Zn 


33-00 


412-50 


Magnesium, 


Mg 


12-67 


158 35 


Zirconium, 


Zr 


33 62 


42020 



It is obvious that the numbers of the oxygen scale are 
just twelve and a half times as large as those in the hydro- 
gen scale ; consequently, dividing the oxygen equivalents by 
12*5 will give the hydrogen numbers, and multiplying the lat- 
ter by the same, numbers will give us the oxygen numbers. 

§ 188. Combining Numbers of Compounds — It has beea 
stated that the equivalent or combining proportion of a com- 
pound body is always the sum of the combining equivalents 

How is one scale translated into the other? [Note. If tlie learner can 
commit the table to memory with the hydrogen equivalents and symbols, 
it will be of great service to him hereafter.] § 188 What is said of com- 
bining numbers of compounds? 

* From Dr. Fownes' Manual, principally on the authority of Berzelius. 

t In the symbols, the Latin names of the elements are employed. 
Eleven of these are not in common use, viz : (1.) Stibium, (2 ) Cuprum, 
(3.) Aurum, (4.) Ferrum, (5.) Plumbum, (6.) H3^draroryrum, (7.) Kalium, 
(8.) Argentum, (9.) Natrium, (10.) Stannum, (11.) Wolfratnium, (from 
the mineral ' Wolfram.') Columbium is frequently represented by the 
symbol Ta, from Tantalum, a name by which the European chemists 
distinguish this metal. 

12* 



I 



138 ELEMENTS AND THEIR LAWS OF COMBINATION. 

of its elements. Strict experiment has established this 
important law, which will receive constant illustration as we 
go on ; at present however, we must accept it as truth, and 
not anticipate, by attempting to give examples which can- 
not be well understood until we have become somewhat 
familiar with chemical language, symbolic illustration, and 
the laws of affinity. 

2. Combination of Volume, 

§ 189. Gaseous bodies, whether elementary or compound, 
combine not only in accordance with the laws just explained, 
but also according to a peculiar law of their own, whereby 
certain volumes of each (^ 30) are required. The volumes in 
which gaseous bodies unite, are either 1 to 1, or 1 to 2, or 
1 to 3, &c. Thus water, which has so often served us as an 
example, is formed of 2 volumes or measures of hydrogen, 
and 1 volume of oxygen. In combining, these three volumes 
are condensed into two. If we take oxygen, hydrogen, 
chlorine, and nitrogen, in the proportions by weight in which 
they combine, or measure the volumes they occupy as gases, 
a very obvious relation will be observed between them ; the 
volume of oxygen being exactly one half that of each of the 
others. 
Thus, 8 grains of oxygen occupy 23-3 cubic inches. 

1 grain of hydrogen, 46-7 

35'41 grains of chlorine, 462 

14*06 grains of nitrogen, 46-5 

The same is true of compound gases, and also all bodies 
which can be raised in vapor, as sulphur, iodine, and mer- 
cury. Solids, which combine with gases, are subject to the 
same law. Sulphur has i the volume of oxygen, and mer- 
cury 4 times. 

^ 190. We can state this truth in another form. If we 
call the weight of a volume of oxygen 1000, then an 
equal volume of hydrogen will weigh 0*0625, and these 
numbers will represent the relative specific gravity of the 
gases. But in water, two volumes of hydrogen unite with 
one of oxygen, and we must, therefore, double the above 

§ 189. How else than by weight do the gases combine? Illustrate 
this. What relation is seen between the equivalent weights and volumes 
of bodies? Name some examples. What of compound gases and so- 
lids? §190. State this truth in another form. 



COMBINATION OF VOLUME. 



139 



hydrogen number, 2 X 0626 = 0125. Now these numbers, 
1000 and 0*125, are exactly the equivalent numbers on the 
oxygen scale, 100* and 12*5, or making hydrogen unity, 
then we have 100 0-f-12-5=r8ox., and 0-125-f-12-5=rl hyd. 
This close relation between the specific gravity of gaseous 
bodies, (i. e. density^) and their combining number, or chem- 
ical equivalents, is universally true, and we might, if space 
permitted, give a long table including these relations. The 
following examples will answer : 



Gases and Vapors. 


Specific Gravities. 


Chemical Equivalents. 


Air=L 


Hydrogen=l. 


By Volume. 


By Weight. 


Hydrogen, 


0-069 


1- 


100 or 1 


H. 1- 


Nitrogen, 


0'97-2 


1403 


100 or 1 


H. 14-06 


Oxygen, 


1-111 


16- 


50 or 4 


8- 


Chlorine, 


2470 


35 64 


100 or 1 


H. 35-41 


Iodine vapor, 


8-70J 


126-30 


100 or 1 


126-36 


Bromine vapor, 


5-393 


78- 


100 or 1 


78-26 


Mercury vapor, 


6-969 


101- 


200 or 2 


101-27 


Sulphur vapor. 


6-648 


96-54 


16-66 or \ 


16-09 



When the numbers in the second column are the same as 
the equivalents, (or with only a fractional difference,) then 
a volume represents an equivalent. The other numbers are 
multiples of the equivalent. Thus, 2x8 = 16, the number 
for the density of oxygen, and sulphur 16x6 = 96, the den- 
sity of sulphur vapor. 

^191. Conclusions, — Therefore we may conclude, that if 
we know the proportions by volume in which two gases 
combine, and also their specific gravities, we can calculate 
the composition of the compound by weight. (2.) Or we can 
foretell the density of a compound by knowing the volumes 
and specific gravities of its elements. (3.) If we know the 
volume and specific gravity of one of the two elements of 
a compound, and of the compound itself, we can then cal- 
culate its composition by weight. (4.) If we know the spe- 
cific gravity and composition of a compound by weight, we 
can then calculate its composition by volume. Many exam- 
ples will be found in elementary chemistry of the practical 
application of these rules. 



Is this relation of density and combining numbers general ? Name 
some of the examples in the table. § 191. What conclusions are drawn 
from the previous statements ? 1st? 2d? 3d? 4th? 



140 ELEMENTS AND THEIR LAWS OF COMBINATION. 

3. Chemical Nomenclature and Symbols. 

^192 Names of the Elements. — Some of the elementary 
bodies have been known from the remotest antiquity, and 
were in common use long before the science of chemistry 
was heard of. Their names are, therefore, quite arbitrary. 
Thus several metals, as Copper, (Cuprum,) Gold, (Aururn,) 
Iron, (Ferrum,) Mercury, {Hydrargyrum,) Silver, {Argen- 
turn,) Lead, (Plumbum,) Tin, (Stannum,) have long been 
known either by the names we now give them, or by those 
Latin terms of which our English names are translations. 
No descriptive meaning is conveyed by such terms as these, 
nor by such as Sulphur and Carbon. The alchemists named 
the metals after the various planets. Thus, Gold was called 
Sol, the Sun ; Silver, Luna, the Moon ; Iron, Mars ; Lead 
Saturn ; Tin, Jupiter; Quicksilver, Mercury ; and Copper was 
called Venus. Hence formerly the astronomical signs or 
symbols of these planets were generally employed by al- 
chemists and mineralogists, to represent the names of these 
metals, and they are still in use in some countries. 

Several of the elements have been named from some 
prominent or distinguishing physical property of color, taste, 
or smell, which they possess : thus Bromine is so called 
from the Greek word, bromos, fetor ; Chlorine, from chloros^ 
green, in allusion to its greenish color ; Chromium, from 
chromos, color, because it makes highly colored compounds, 
as chrome-yellow ; Glucinum, from glukus, sweet, from the 
sweet taste of its salts ; Iodine, from ion, a violet, and 
eidos, in the likeness of; and so for many others. Another 
class of names has been contrived from what was supposed 
to be the characteristic attribute of the body in combination. 
Thus, Oxygen was so named from the fact, that many 
of its compounds are acids, from the Greek, oxus, acid, and 
gennao, I produce. Hydrogen is from hudor, water, and 
gennao, I produce. We might thus go through the whole 
list, but it is unnecessary, as we shall have again to give the 
etymology of all these words, when we speak of each ele- 
ment. 

§ 193. Names of Compounds. — All chemical compounds 

§ 192. Whence have some of the elements, as copper, &c., received 
their names? What did the alchemists call the metals ? On what other 
principles have some been named ? Give instances.. 



CHEMICAL NOMENCLATURE AND SYMBOLS. 141 

derive tlieir names from one or more of their constituents, 
according to certain fixed and simple rules, which we must 
very briefly explain. (1.) When two elements unite, the 
compound is called Unary, from his, twice ; thus, water, 
sulphuric acid, oxyd of silver, and oxyd of iron, are binary 
compounds. (2.) Compounds of binary combinations with 
each other, as of sulphuric acid with soda, forming sulphate 
of soda, or Glauber's salts, (and the salts, generally so call- 
ed,) are called ternary compounds, (from ter, thrice.) (3.) 
Compounds of salts with each other, (as in the case of alum, 
which is a compound of sulphate of potash and sulphate 
of alumina,) are called quaternary compounds, from quatuor, 
four. 

^ 194. All the compounds of oxygen with the other ele- 
ments are called either oxyds or acids. Thus, water in chem- 
ical language is the oxyd of hydrogen ; the chemical name 
of potash is the oxyd of potassium. It has been before 
stated, that oxygen forms compounds with all the other 
elements, (§ 186.) Some of these compounds have what 
we commonly call acid* properties : thus, the compounds 
of oxygen and sulphur are called acids, and not oxyds. 
Oxyds are divided into two classes ; (a) neutral oxyds, like 
water ; (b) alkalinef oxyds and bases,:j: like potash, alumina. 
When the same element unites with oxygen in more than 
one proportion, (^ 183, 2d,) forming two or more oxyds, then 
they are distinguished by the Greek prefix, proto, {protos, 
first,) applied to that body which has the least portion of 
oxygen, which is called the proioxyd ; deuto, {deuteros, sec- 
ond,) is prefixed to the next degree of oxidation, giving us 

§193. How are compounds named? 1st binary? 2d ternary? 3d 
quaternary? § 194. What are the oxygen compounds called? Give in- 
stances. How are oxyds described? Notes. What are acids? What al- 
kalies ? What bases ? 

* Acids are known by their taste in some cases, and by their power 
of turning the vegetable blues to red ; but more particularly by their 
power of uniting with and saturating alkalies and other bases. 

t Alkalies are soluble bodies, with a hot, acrid taste, which have the 
power of saturating acids, and of turning the reddened vegetable blues 
to blue or green. 

t Base is a term given to all oxyds which are not acids : it is a more 
general and comprehensive term than alkali. In fact, all bodies, simple 
and compound, are properly divided into bases and acids, or electro-posi' 
tive and electro -negative bodies. 



142 ELEMENTS AND THEIR LAWS OF COMBINATION. 

the term deutoxyd ; trito, (tritos, third,) to the body contain- 
ing still more oxygen than the deutoxyd. The oxyd which 
contains the largest dose of oxygen with which the body 
can unite, is also called the peroxyd, from the Latin, per, 
which is a particle of intensity in that language. Thus 
there are two oxyds of hydrogen ; the protoxyd (water) 
and the per oxyd ; there are three oxyds of manganese ; 
(1.) the protoxyd, (2.) the deutoxyd, (3.) the per oxyd of man- 
ganese. Some oxyds are formed in the proportion of 
2 to 3, or once and a half. Such oxyds are distinguished 
by the term sesquioxyd, from the numeral sesqui, (once 
and a half.) Certain inferior oxyds are called suboxyds. 

^ 195. The binary compounds of chlorine, and some other 
elements which resemble oxygen in their manner of com- 
bination and in their relations to electrical decomposition, 
are also distinguished in the same manner as oxygen. Thus, 
with the other elementary bodies : 

Chlorine forms Chlorids. 



Bromine 


a 


Bromids. 


Iodine 


a 


lodids. 


Fluorine 


a 


Fluorids. 


Oxygen 


a 


Oxyds. 



§ 196. The binary compounds of sulphur analogous to the 
oxyds are called sulphurets, and not sulphids. The prefix 
bi (double) is more commonly used before the double un- 
ions of chlorine, sulphur, &c., than deuto, which is used be- 
fore the oxyds. Thus, it is more usual to say bichloride 
of carbon, and bisulphuret of iron, than deutochloride 
of carbon, and deutosulphuret of iron. When the name 
of the element to which this prefix is made begins with 
a vowel, the consonant ?i is introduced as making a more 
euphonious word ; thus we say biniodid of lead, rather than 
bi-iodid of lead. Compounds of phosphorus and carbon, 
with electro-positive elements are distinguished by the 
termination uret, like those of sulphur ; thus, we say, the 
sulphuret of carbon, carburet of iron, and phosphuret of lead. 
In all such cases, the name of the element which most re- 
sembles oxygen, (i. e. the electro-negative element,) is that 

Explain the terms expressing different degrees of oxydation, and their 
Use. 1st, proto. 2d, deuto. ^d, trito. 4th, per. 5th, sesqui. 6tk, 
sub. § 195. How are the binary unions of chlorine, &c., named? 
Give instances § 196. How is the term " bi'' used ? 



CHEMICAL NOMENCLATURE AND SYMBOLS. 143 

which Stands first in the name of these compounds, and which 
has the termination affixed to it. Thus, one of the com- 
pounds of chlorine and phosphorus is called chlori^of phos- 
phorus, and not phosphuret of chlorine ; sulphuret of carbon, 
and not carburet of sulphur, 

^ 197. The acid compounds of oxygen (^mfl^ry compounds) 
are named from the substance in combination with the oxy- 
gen, with the addition of the termination zc, the word acid 
being always appended. Thus, one of ^he compounds of ni- 
trogen and oxygen is termed nitric acid ; of chromium and 
oxygen, chromic acid. 

If two acid compounds of oxygen are formed with an ele- 
ment, the termination ous is applied to that which has the 
least oxygen ; thus we have sulphurous acid and sulphuric 
acid, as the names for two very dissimilar acids of sulphur. 

Sometimes a compound has been discovered containing less 
oxygen than that compound which has already received the 
termination ous ; then the term hypo is prefixed, (from the 
Greek hupo, under,) and we then have the term hyposulphu- 
rous ; or hypo sulphuric, provided an intermediate compound 
is formed between the sulphurous and sulphuric acid. On 
the same plan, we say hyperchloric acid, (from huper, above,) 
to distinguish the acid of chlorine having a higher proportion 
of oxygen than chloric acid before named ; and perchloric acid 
has #ie same meaning, and may be used with equal pro- 
priety. All other analogous acids are named on precisely 
the above principles. 

§ 198. Sulphur acids and hydrogen acids are those where 
sulphur and hydrogen take the place of oxygen. Thus, suU 
pho-arsenic-acid is an acid compound of arsenic and sulphur. 
Hydrochloric acid is the acid formed from the union of hy- 
drogen and chlorine.* In the same way, we have hydrobro- 
mic, hydrofluoric, and hydriodic acids, as acids of bromine, 
fluorine, and iodine. 

In the names of sulphur, iodine, &c., which element stands first? 
§ 197. How are the acid compounds of oxygen named ? Explain the 
use of the terminations " ic" and " ous" How is hypo used in this con- 
nection, and how hyper? §198. Sulphur acids and hydrogen acids are 
how named ? 

* In strict uniformity to rule, the term chloroJiydric is correct, hut use 
has estahlished the other. The same remark is true of bromohydric, 
fluohydric, and iodohydric acids. 



I 



144 ELEMENTS AND THEIR LAWS OF COMBINATION. 

^ 199. (2.) Ternary compounds, or salts, are named from 
the acid which they contain ; the acid termination ic being 
changedP into ate, and ous into ite. Thus, the sah formed 
from the union of soda and nitric acid is called the nitrate 
of soda ; and that formed with nitrous acid is called the 
nitrite of soda ; the salts of hyponitrous acid are called hy- 
ponitrites, and of hyperchloric acid, hyperchlorates, &c. 
The species is always indicated by the oxyd ; thus, the ni- 
trate of lead is the same as the nitrate of the oxyd of lead, 
and nitrate of soda is the same as nitrate of the oxyd of 
sodium ; the word oxyd being understood, is generally 
omitted. A 5^sulphate has twice, and a sesquisulphdiie 
once and a half as much acid as a sulphate. The excess 
of base in subsalts is sometimes expressed by the Greek 
prefix, di, twice ; thus, the dichromate of lead has twice as 
much of the base lead, as the chromate of lead. 

§ 200. (3.) Quaternary Compounds, — The double salts 
are named from their bases ; thus alum, which is formed of 
sulphate of alumina and sulphate of potash, is called simply 
double sulphate of alumina and potash. The chlorid of 
potassium and platinum is another double salt formed from 
the union of a chlorid of platinum and chlorid of potas- 
sium. 

§ 201. The chemical nomenclature, when once understood, 
enables us after a little use to form in most cases from the 
mere name of the compound substance, a correct idea of its 
composition, and of the proportions of its constituents. 
This great advantage is possessed by no other science, and 
cannot be too highly estimated. There are a good many 
compounds however, that have been discovered of late 
years, for which this nomenclature provides no names. But 
we have certain written expressions, by means of which we 
can convey an idea of all chemical compounds with a math- 
ematical precision and great convenience. We refer to 
the— 

§ 202. Chemical Symbols of the Elements. — In the table 
of Elementary Bodies (^ 187) the " symbols" of the several 



§ 199. How are salts named ? Give examples. How are the species 
named? What is a, hi diud sesqui sulphate? What meaning has the 
prefix di? §200. (3.) How are double salts named? Give examples. 
§ 201. What great advantage has the chemical nomenclature ? § 202. 
What are chemical symbols ? 



CHEMICAL NOMENCLATURE AND SYMBOLS. 145 

elements will be found opposite to their names. The sym- 
bols are merely the first letter of each name^ or the first two, 
when more than one element begins with the same letter ; 
thus O stands for Oxygen, and Os for Osmium ; P stands 
for Phosphorus ; PI for Platinum, and Pd for Palladium. 
The second letter in all such cases is small, a capital letter 
being uniformly used for the first. The Latin names are 
invariably used for the abbreviation^ and for this reason there 
are eleven symbols, unlike the common names of the ele- 
ments they represent. (See note to § 187.) Prof. Berzelius 
contrived the system of symbols now in use, and by a happy 
thought, he made each symbol represent not merely the 
substance for which it stands, in the abstract, hut one equivalent 
of each substance. Thus O stands not for oxygen in gen- 
eral, but for one equivalent of that element, or, hydrogen 
being unity, the number 8. O and 8 are, therefore, inter- 
changeable expressions, while O^, O^, &c., represent 2x8 
and 3x8, or 16 and 24, according to the second law of 
chemical combination, (§ 183.) 

Compounds are represented by using merely the symbols, 
and sometimes uniting them by the sign of addition, ( + .) 
Thus water will be represented by HO or H + 0, which 
means one equivalent of each element, 1+8 = 9, which is 
the combining number of water. Protoxyd of lead is thus 
written PbO, or Pb + 0. 

^ 203. When more than one equivalent of an element is in 
combination, we then prefix a number expressing it, like an al- 
gebraic co-efficient, (as 50,) or the number may be applied 
above on the right, (as 0^,) or below on the right, (as O^,) 
each of these expressions means five equivalents of oxygen. 

Thus we can write nitric acid, N50, or NO^, or NOg, the 
latter being the usual mode ; sometimes but not often, the 
4- or comma (,) is used between them, as N + O., N, O^. 
Such expressions are called formul(£, thus the formula for 
sulphuric acid is SO 3, or S + O3, or S, O3, from which we 
know that the combining number of sulphuric acid islG + Sg, 
or 16 + 24 = 40. When two compounds unite to form a new 

Give examples. What names are abbreviated ? Whose contrivance 
are the symbols? For what does the symbol stand? Illustrate. How 
are compounds represented ? Give examples on the black-board. § 203. 
How is more than one equivalent expressed? Show the different modes 
in which nitric acid is expressed ? How is the miion of compounds ex- 

13 



146 ELEMENTS AND THEIR LAWS OF COMBINATION. 

body, the sign +> or (,) is used between them; thus, sul- 
phate of oyxd of iron is written, FeO + SO^, or FeOjSOg. 
The small figures apply only to the letters to which they are 
attached ; larger figures used before the compound, apply to 
the whole formula; thus, SSOg means three equivalents of 
sulphuric acid ; but the sign + prevents the passage of this 
meaning beyond the sign. Thus 2Fe + S03 means two 
equivalents of oxyd of iron and one of sulphuric acid ; in 
order to make the figures apply to both, we must write it 
2(Fe + S03)or2(Fe,S03.) 

In chemical symbols the oxygen or element most nearly 
resembling it, (i. e.,the electro-negative element,) is placed 
last ; the base (or electro-positive element) being placed 
first. Thus we say, SO 3 for sulphuric acid, and not O3S. 
The compound of sulphuric acid (SO3) and water, which is 
common oil of vitriol, contains 2 equivalents of water, only 
one of which is however chemically combined as a base 
with the acid. We can make this apparent to the reader in 
constructing the formula thus, HOjSOg + HO; the comma 
signifies a closer union than the +, and the first equivalent 
of base is in intimate union with the acid, forming a sulphate 
of water, while the second portion is combined with this 
sulphate. Compounds which contain water, like common 
sulphuric acid, nitric acid, and many mineral bodies, are 
termed hydrous, 

^ 204. The symbols are sometimes abbreviated, still fur- 
ther, to simplify the expression of very complex combina- 
tions. This is done by expressing one equivalent of oxygen 

by a dot, two, by two dots, &c. Thus S signifies the same 
as SO 3, (sulphuric acid.) Common crystalline alum is 
written in full, thus, 

Al,03,3S03 + KO,S03 + 24HO. 
We can conveniently condense this long expression ; thus, 

llS3 + KS+24H. 
The short line under the Al signifies two equivalents of the 



Tell the difference between the small and large figures. Which ele- 
ment is placed first in symbols? Illustrate. How can we make the pe- 
culiar construction of hydrous sulphuric acid seen ? What are hydrous 
bodies? §204. Illustrate on the black-board the abbreviation of symbols 
in the case of alum. 



CHEMICAL AFFINITY. 



147 



base. Sometimes the double equivalent of base is denoted 

by a black letter thus, Al, in place of the line beneath. In 
Berzelius's original symbols the short line is made through 
the type in the lower half. Sulphur is in like manner signi- 
fied by a comma; thus, bisulphuret of iron, Fe,So, may be 

?> 
more shortly written, Fe. The constant use of these sym- 
bolic expressions in the elementary chemistry will soon 
familiarize the learner with their use and meaning. They 
have contributed very much to the progress of the science, 
and are invaluable as a ready means of comparing as well as 
expressing the composition of compound bodies. 

4. Chemical Afinity, 

§ 205. We have already explained (§ 12 and § 13) what 
is meant by chemical affinity, as the power which unites two 
or more unlike bodies to form a third substance, whose 
properties differ from those of its constituents. Chemical 
affinity, or the capability of union, is not possessed alike 
by all bodies. Oxygen is the only element capable of form- 
ing chemical compounds with all other elements.* Carbon 
can unite with oxygen, sulphur, hydrogen, and some other 
bodies, but no compound has been formed between it and 
gold, silver, fluorine, aluminium, iodine, bromine, &c. It 
is, therefore, said to have no affinity for these bodies, or 
no capability of union with them. This power of union 
among bodies, -or affinity, is exceedingly different in de- 
gree, and is much affected by many circumstances. Thus 
a body A may unite with a body B, forming a third body 
AB ; but if a body C, had been present, A might have so 
much more affinity for C than it has for B, as to unite with 
it, forming AC, while B would remain unaffected. For 
example, sulphuric acid and soda will unite to form Glau- 
ber's salts or sulphate of soda, but if soda and baryta had 
both been present, and sulphuric were added, only the sul- 
phate of baryta, (or heavy spar,) would be formed, and the 
soda would remain disengaged, unless there was sulphuric 

How is sulphur signified by symbols? § 205. What is chemical affin- 
ity? Is it equal in all bodies? Illustrate by examples. 



* Except perhaps with fluorine. 



148 ELEMENTS AND THEIR LAWS OF COMBINATION. 

acid enough to satisfy all the baryta and soda too. This is 
what is sometimes called *' elective affinity," as if the acid 
chose out the baryta rather than the soda. 

§ 206. The more unlike, as a general thing, any two bodies 
are in chemical properties, the stronger is their disposition to 
unite. The metals, as a class, have very little disposition 
to unite with each other, and do so generally, not in chem- 
ical proportions ; such compounds of metals being called al- 
loys. But the metals do unite with oxygen, chlorine, sulphur, 
&;c., forming fixed and determinate compounds. The alka- 
lies, potash and soda, form no proper compound with each 
other, and their alkaline properties are not altered by such 
union. Sulphuric and nitric acid may be mingled in any 
proportion, but no new compound is formed, the mixture is 
still acid. But if the potash and soda be put with the nitric 
and sulphuric acid, separately, and in their combining pro- 
portions, the result will be two compound bodies, having 
neither acid nor alkaline properties. If the nitric acid is 
put to its equivalent of potash, we shall have saltpetre, or 
nitrate of potassa, while the sulphuric acid in like manner 
will unite with its equivalent of soda, forming sulphate of 
soda, or Glauber's salts. 

§ 207. Solution is the result of a feeble affinity, but one in 
which the properties of the dissolved body are unaltered ; 
thus, sugar is dissolved in all proportions in water or alcohol, 
and a drop of the solution may be mingled in an ocean of 
water. Camphor is soluble in alcohol, in any proportion, but 
the addition of water to the solution will cause the camphor 
to be thrown down. Gum is soluble in water, but not in alco- 
hol. We have already seen, that the solution of various 
salts in water would produce cold (§ 111) from the change 
of state in the body dissolved. 

§ 208. The circumstances which modify the action of af- 
finity are numerous, some of which we may briefly notice. 
We have said (^ 16) not only that chemical affinity was ex- 
cited between unlike particles, but only at insensible dis- 
tances. Intimate contact among particles is, therefore, in 
the highest degree necessary to promote union. Any cir- 
cumstance which favors such contact will increase the ac- 



What is meant by "elective affinity?" § 206. What principal condi- 
tion of affinity is named? Illustrate. § 207. What is said of solution ? 
§ 208. What circumstances modify or are essential to affinity ? 



CHEMICAL AFFlNlTf. 149 

tivity of, or disposition to, chemical combination. Sohition 
brings particles near together, and leaves them free to move 
among each other ; substances in a state of solution have, 
therefore, an opportunity to unite, which they do not possess 
when solid. Carbonate of soda and tartaric acid, for ex- 
ample, both in a dry state, would never unite, but the addi- 
tion of water will at once, by dissolving them, bring about 
a union. Heat will often cause union to take place, being, 
in fact, a most powerful means of solution. Sand or silica 
will not soon unite with soda or potash, by contact or aqueous 
solution, but if the mixture in proper proportions be strongly 
heated, union takes place and glass is formed. Dry flowers of 
sulphur will not unite with cold iron, but if the iron be 
heated to redness, or the sulphur be melted, then a vigorous 
union takes place, and a sulphuret of iron results. 

Cohesion (^ 10) is strongly opposed to chemical union, or 
affinity, and any means which will overcome it, will pro- 
mote the union of the elements. Solution and heat both 
act by overcoming cohesion ; and the fine mechanical divis- 
ion of a body, or pulverization, does the same. 

^ 209. Bodies in the nascent^ state (as it is called) will 
often unite, when under ordinary circumstances no affinity 
is seen between them. Thus hydrogen and nitrogen gases 
under ordinary circumstances, do not unite if mingled in the 
same vessel ; but when these two gases are set free at the 
same time, from the decomposition of some organic matter, 
they readily unite, forming ammonia. The same^s true of 
carbon under the same circumstances, which will then unite 
in a great variety of proportions with hydrogen and nitrogen, 
although no such union can be effected among these bodies 
separately. 

^210. The quantity of matter as well as the order and con- 
dition in which substances may be presented to each other, 
often exerts an important influence on the power of affinity. 
Thus vapor of water when passed through a gun barrel 
heated to redness, will be decomposed, the oxygen uniting 
with the iron, while the hydrogen escapes at the other end of 

How does solution favor it ? Ill ustrate. How does heat favor it ? Ill us- 
trate. How does cohesion aifect it? What counteracts cohesion? 
§209. What of bodies in the nascent state? Illustrate this. § 210. 
What of quantity of matter? Give an example. 

' —— ^ - ■ 

* From nascenSf being produced, or in the moment of formation. 

13* 



150 ELEMENTS AND THEIR LAWS OF COMBINATION. 

the tube. On the contrary, if hydrogen gas is passed over oxyd 
of iron in a tube heated to redness, the oxygen of the oxyd 
unites with the hydrogen, leaving metallic iron, v^hile steam 
(formed from the union of the hydrogen with the oxygen 
from the iron,) issues from the open end of the tube. Numer- 
ous examples of this sort might be given, where the play 
of affinities seems to be determined by the preponderance 
of one sort of matter over another, or by the peculiar con- 
dition of the resulting compounds, as regards insolubility, 
or the power of vaporization. 

^ 21 1. The presence of a third body often causes a union, 
or the exertion of the force of affinity, when this third body 
takes no part in the changes which happen. Thus, oxygen 
and hydrogen gases may be mingled without any combina- 
tion taking place between them, although a strong affinity 
exists. If, however, a portion of platinum in a state of very 
fine division, (spongy platinum,) be introduced into the mix- 
ture, union takes place, sometimes slowly, but more often 
with an explosion, the platinum being previously heated to 
redness solely from the great condensation of the gases 
which takes place in its numerous pores. Advantage is 
taken of this fact in constructing the common instrument for 
lighting tapers by a stream of hydrogen falling on spongy 
platinum. No change is suffered in this case by the plati- 
num, which seems to act by its presence only. Berzelius 
has proposed the term catalysis, from the Greek kata^ 
by, and %wo, to loosen, to express the peculiar power 
which some bodies possess of aiding chemical changes 
by their presence merely. We shall have occasion to 
refer to this subject again. The case of the platinum is 
much more intelligible than many other instances of con- 
tact-union and decomposition of which chemistry offers 
examples, since it appears to act by its power of condensation, 
to bring the particles within combining distance. 

5. Atomic Theory. 

§ 212. We have already (^ 7 and ^ 8) said something of 
atoms as being the smallest conceivable state in which mat- 
ter exists. As all ponderable matter is assumed to be 
formed by an aggregation of a series of these atoms, the in- 

§211. What is presence? Illustrate this. What other term ex- 
presses these cases? §212. What is the atomic theory ? 



ATOMIC THEORY AND SPECIFIC HEAT X)lf ATOMS. 151 

teresting question at once arises, do the chemical eqnivaieiits 
or combining weights of the several elements express the 
relative weights of their atoms ? Dr. Dalton first proposed 
the view now universally accepted, which assumes this to 
be the fact. All that has been said in this chapter on the 
combining weights of bodies, &c., has been the result of 
rigorous chemical investigation, and is capable of demonstra- 
ble proof. Dalton 's hypothesis of the relative weights of 
ultimate atoms is only theoretical, but has been found to 
conform in a remarkable degree to the results of experience. 
We may feel some good degree of certainty in the belief 
that we k7iow the actual relation of weight between the ulti- 
mate atoms or molecules of the elements. There is no 
doubt that the atom of oxygen is eight times heavier than 
that of hydrogen ; but we know nothing of their actual 
weight. 

§ 213. We can now, perhaps, better understand why th© 
equivalent numbers of bodies should always be multiples of 
each other. If the atom of oxygen be represented by eight, 
(and we cannot conceive of an atom as being divided,) then 
any compound containing more than one atom of oxygen, 
must have twice, thrice, or four times eight, and so on. On 
this view of atoms, all the four great laws of chemical com- 
bination (§ 1B3) receive a remarkable corroboration, as a little 
reflection will show. The atomic weight of a body is there- 
fore as correct an expression, as its equivalent weight, or 
combining proportion. We might easily illustrate this theory 
to the senses in a gross way, by a series of spheres, so 
marked as to represent the several atoms of elementary 
bodies, the union of which would show the compound re- 
sulting from the union of atoms. 

6. Specific Heat of Atoms. 

^ 214. Specific heat has already been explained, (§ 106.) 
If in place of comparing equal weights of different bodies 
together, we take them in atomic proportions, we shall find 
the numbers representing the specific heat of lead, tin, zinc, 
copper, nickel, iron, platinum, sulphur, and mercury, to be 
identical ; while tellurium, arsenic, silver, and gold, although 
equal to each other, will be twice that of the nine previous 

§ 213. What help does it give in understandiii|2: chemical facts ? § 214- 
What relation has specific heat to the atomic theory? 



152 CRYSTALLTZATIOI^. 

bodies, and iodine and phosphorus will be four times as 
much. The general conclusion drawn from these and other 
similar facts is, that all atoms of simple substances have the 
same capacity for heat. The specific heat of a body would 
thus afford the means of fixing its atomic weight. There 
can be no doubt of the truth of this in numerous cases, but 
experiments are still wanting to show it to be universally 
true. 

Compound atoms have in some cases been shown to have 
the same relations to heat as the simple. This is true of 
many of the carbonates and some sulphates ; but a more 
minute consideration of the atomic theory would be out 
of place in a work of this extent. 



II. CRYSTALLIZATION. 

1. Nature of Crystallization and Primary Forms of Crystals, 

§ 215. Nature of Crystallization. — The forms of living 
nature, both animal and vegetable, are determined by the laws 
of vitality, and are generally bounded by curved lines and sur- 
faces. Inorganic or lifeless matter is shaped by a different 
law. Geometrical forms, bounded by straight lines and 
plane surfaces, take the place in the mineral kingdom which 
the more complex results of the vital force occupy in the 
animal and vegetable world. The power which determines 
the forms of inorganic matter is called crystallization. A 
crystal is any inorganic solid, bounded by plane surfaces 
symmetrically arranged, and possessing a homogeneous 
structure. 

Crystallization is, then, to the inorganic world what the 
power of vitality is to the organic ; and viewed in this, its 
proper light, the science of crystallography rises from the 
low station of being only a branch of solid geometry, to oc- 
cupy an exalted philosophical position. We see, therefore, 
the importance of devoting a brief space to this subject in 
considering the general principles of Chemical Philosophy. 

The cohesive force in solids (^ 60) is only an exertion of 
crystalline forces, and in this sense no difference can be 
established between solidification and crystallization. The 

§ 215. What parallel is drawn between the forces of living and inor- 
ganic nature ? What is crystallization said to be ? What is the cohesive 
force ? 



NATURE OF CRYSTALLIZATION. 153 

forms of matter resulting from solidification may not always 
be regular, but the power which binds together the mole- 
cules * is that of crystallization. 

§ 216. Circumstances injluencing Crystallization. — Solu- 
tion is one of the most important conditions necessary to 
crystallization. Most salts and other bodies are more soluble 
in hot than in cold water. A saturated hot solution will on 
cooling usually deposit crystals. Common alum and 
Glauber's salts are examples of this. Solution by heat or 
fusion also allows of crystallization, as is seen in the crys- 
talline fracture of zinc and antimony. Sulphur crystallizes 
beautifully on cooling from fusion, and so do bismuth and 
some other substances. The slags of iron furnaces and 
scoriae of volcanic districts present numerous examples of 
minerals finely crystallized by fire. The glass, which cools 
slowly after long fusion, in the clay fire-pots of our glass 
houses, has often beautiful star-formed opaque white crystals 
found in it, and the whole mass of the glass sometimes 
becomes crystalline and opaque. Blows and long continued 
vibration produce a change of molecular arrangement in 
masses of solid iron and other bodies, resulting often 
in the formation of broad crystalline plates. Rail-road 
axles are thus frequently rendered unsafe. In short, any 
change which can disturb the equilibrium of the particles 
and permits any freedom of motion among them, favors the 
re-action of the polar or axial forces (§ 217) and promotes 
crystallization. 

Magnetism influences and promotes crystallization* 

When nitrate of mercury on a glass 

plate is placed over the poles of an ^^^ 
electro-magnet, as in the figure, ^^ 
crystallization takes place in the 
curved lines here shown. By sub- 
stituting a plate of copper for the 
glass, it is curiously etched in the 
magnetic curves by the acid of the 
silver salt. These experiments may be much varied by the 
ingenuity of the learner. The recent observations of Mr. R- 
Hunt have given us much new information on this point. 

§216. Name some circumstances which influence crystallizatioiL. 
What is said of the power of magnetism in this respect? 

* Molecule, a diminutive, from moles, a mass. This term is preferable 
to * atom' or * ultimate particle' as implying no theory, wliich both th^ 
others do. 




154 



CRYSTALLIZATION. 



^217. Polarity of Molecules. The laws of crystalliza- 
tion show that the molecules (or ultimate particles) of mat- 
ter have polarity. That is, these molecules have three 
imaginary axes passing through them, whose terminations, 
ox poles, are the centre of the attractions (^ 10) by which a 
series of similar particles are attracted to each other to form 
a regular solid. These molecules are either spheres [a) or 
ellipsoids, (c,) and the three axes (N. S.) are always either the 
fundamental axes or the diameters of these particles. In the 




y^/^ 


»k\ 


^ 


L 


s 






/. 



sphere (a) these axes are always of equal length and at right 
angles to each other, and the forms which can result from 
the aggregation of such spherical particles can be only sym- 
metrical solids, such as the cube and its allied forms. The 
cube drawn about the sphere «, may be supposed to be made 
up of an infinite number of little spheres (6) whose similar 
poles unite N. and S. In the ellipsoid (c) all the axes may 
vary in length, giving origin to a vast diversity of forms. 
All matter not subject to the vital force is endowed with such 
polarity inherent in its molecules.^ 

§218. Crystalline Forms. — The mineral kingdom pre- 
sents us with the most splendid examples of crystals ; 
yet, in the laboratory we can imitate the productions of 
nature, and in many cases produce beautiful forms from the 
crystallization of various salts, which have never been 



§ 217. What do the laws of crystallization show? What are the axes 
of molecules? What forms have the molecules of bodies? What forms 
can come from the spherical particles? How may the structure of the 
cube be shown? How are the axes of the ellipsoid? To what matter do 
these axial attractions belong ? § 218. How are the complex forms of 
crystals arranged and simplified ? 

* We thus see that atoms, or molecules, are only the centres of sev- 
eral forces, whose aggregate results we call matter. Under the influence 
of heat, the crystallogenic attraction loses its polarity and force, and the 
body becomes liquid or gaseous. The return to a solid state can occur 
again only when the attractions become polar or axial. 



PRIMARY FORMS OF CRYSTALS. 



155 



^ f 


.-J 


?- -A 


.'^^ 


^^' 












■^ a 




^y^ 




observed in nature. The learner who is ignorant of the 
simple laws of crystallography, sees in a cabinet of crystals 
an unending variety and complexity of form, which at first 
would seem to baffle all attempts at system or simplicity. 
Numerous as the natural forms of crystals are, however, 
they may be all reduced to six classes, comprising only 
thirteen or fourteen forms, which are called the Primary 
forms, because all other crystalline solids, however complex 
or varied, may be formed from them by certain simple 
laws. 

^219. Primary Forms. — The first class of primary forms 
includes the cube, (1,) the octahedron, (2,) and the dodecahe- 
dron, (3.) The 
faces of the cube 
are equal squares. 
The eight solid 
angles are similar, 
and also the twelve 
edges. The three 1 2 3 

axes are equal, {aa, ^^, cc,) and connect the centres of op- 
posite faces. The regular octahedron (2) consists of two 
equal, four-sided pyramids placed base to base. The six 
solid angles are equal, and so also the edges, which, as in 
the cube, are twelve in number. The plane angles are 60°, 
and the interfacial 109° 28' 16''. The axes connect the 
opposite angles ; they are equal and intersect at right angles. 
This class is also called the monometric, {monos, one, and 
metron^ measure,) the axes being equal. 

^ 220. The second class includes the square prism, (4,) and 
square octahedron, (5.) In the square prism, (4,) the eight 
solid angles are right angles and 
similar, as in the cube. The 
eight basal edges are similar, but 
differ from the four lateral. The 
two basal faces are squares, the 
four lateral are parallelograms. 
The axes connect the centres of 
opposite faces and intersect at 4 5 

right angles. Square prisms vary in the length of the ver- 
tical axis, [a a,) which is hence called the varying axis ; the 



y 


CO 


-7 




7, 


c 


-i 


..-^^ 


„.^ •• 


"*• 


/ 






..--- 


a/ 


/ 



§ 219. Describe the first class of primary forms. § 220. What are the 
forms of the second class? Describe them. 



156 



CRYSTALLIZATION, 








lateral axes, (55, ec,) are equal. This class is also called the 
dimetric, (dis, twofold, and meiron, measure.) 

§ 221. The third class contains the rhombic prism, (6,) the 
rectangular prism, (7^) and the rhombic octahedron, (8.) 

The rhombic prism, 
(6) has two sorts of 
edges, two acute and 
two obtuse. The 
solid angles are, there- 
forey of two kinds, four 
6 7 g obtuse aBd four acute. 

The axes are unequal and cross at right angles. The lat- 
eral connect the centres of opposite edges, hi, ce. The 
basal faces are rhombic. The rectangular prism (7) has all 
its solid angles similar. There are three kinds or sets of 
edges, four lateral, four longer basal and four shorter basal. 
The axes connect the centres of opposite faces and intersect 
at right angles. The three are unequal. The rhombic 
octahedron (8) has three unequal axes connecting opposite 
solid angles. All the sections in this solid are rhombic. 
This class is also called the trimetric, from tris, threefold, 
and metron, measure. 

^ 222. The fourth class contains the oblique rhombic 
prism, (9,) and the right rhomboidal prism, (10.) The oblique 
rhombic prism is represented in the figure (9) as inclining 
away from the observer, the prism 
being in position when standing on 
its rhombic base. The upper and 
lower solid angles in front are dis- 
similar, one obtuse and the other 
acute. The four lateral solid angles 
9 10 are similar. Two of the lateral 

edges are acute and two obtuse, and the same is true of the 
basal. The lateral axes are unequal ; they connect the centres 
of opposite lateral edges and intersect at right angles. The 
vertical axis is oblique to one lateral axis and perpendicular 
to the other. The right rhomboidal prism (10) has two obtuse 
and two acute lateral edges, and four longer and four shorter 
basal edges. The solid angles are of two kinds, four obtuse 



"M 



^-^ 


I** 


^^^ 


fi,^ ■ 


\J 


f? 







§ 221. What forms make up the third class ? Describe them. § 222. 
What forms does the fourth class contain? How do they differ? What 
©ther names have the first, second and third classes? 



PRIMARY FORMS OF CRYSTALS. 



157 



and four acute. The axes connect the centres of opposite 
faces ; one is oblique, the others cross at right angles. 
This is also called the monoclinate, {monos one, and clino to 
incline,) having one inclined axis. 

§ 223. The fifth class includes the oblique rhoml^oidjl prism. 
In this solid only those parts diagonally opposite 
are similar, and consequently it has six kinds of 
edges. The axes connect the centres of oppo- 
site faces. They are unequal, and all their in- 
tersections are oblique. This is called the 
triclinate class, from [tris, three, and clino, to 
incline, the three axes all being obliquely inclined. 

^ 224. The sixth class includes the hexagonal prism, (12,) 
and the rhombohedron, (13 and 14.) The hexagonal prismhd.^ 
tvvelve similar angles, and the same number of similar basal 
edges. The lateral edges are six in number, and similar. 
The lateral axes are equal, and cross at 60"^, connecting the 
centres of opposite lat- 




eral faces 
edges. 
The 
a solid 
are all 



or lateral 





rhombohedron is 

whose six faces 
rhombs. The 
two diagonally opposite 
solid angles [a a) consist 12 13 

of three equal obtuse or equal acute plane angles, and the 
diagonal connecting these solid angles is called the vertical 
axis, (a a.) When the plane angles forming the vertical 
solid angles are obtuse, the rhombohedron is called an obtuse, 
(13,) and if acute, it is called an acute rhombohedron, 
(14.) The three lateral axes are equal, and intersect at 
Angles of 60° ; they connect the centres of opposite lateral 
edges. This will be seen on placing a rhombohedron in 

f)Osition and looking down upon it from above. The six 
ateral edoes will be found to be arranged around the vertical 
axis, like the sides of a hexagonal prism. 

§ 225. The mutual relations of the primary forms are well 
shown in the foregoing arrangement. Thus, in each of the 



§223. What solid is included in the fifth class? § 224. Name the 
two solids in the sixth class of primary forms. How are the hexagonal 
prism and rhombohedron related ? How are rhombohedrons distinguished ? 
§ 225. What is said of the relations of primary forms ? What six fun- 
damental forms are named l 

14 



158 CRYSTALLIZATION. 

six classes the first named solid alone is, properly consid- 
ered, a primary form, the others in each class being fre- 
quently found as secondaries to these. I'he six fundamental 
forms are the ciihe, square prism, right rectangular prism, 
oblique rhombic prism, right rhomboidal prism, oblique rhom- 
hie prism, oblique rhomboidal prism, and the hexagonal prism^ 
or rhombohedron. 

2. Cleavage. 
^ 226. Common isinglass, (mica,) as is well known, will 
split into thin leaves or plates, which can be subdivided as 
long as our comparatively clumsy instruments will allow. 
This property depends on the crystalline structure of the min- 
eral, and is called its cleavage. Many other minerals possess 
the sanie property. Thus, galena (sulphuret of lead) can 
be broken only into cubes, or in directions parallel to one or 
more of the faces of a cube. It differs, however, from mica, 
in having three cleavage directions, at right angles to each 
other. Fluor-spar, which is often found in cubes, can, by 
cleavage of the solid angles, be made into regular octahe- 
drons. Calc'spar also admits of easy cleavage in three 
directions, but yields only rhombohedrons. 

Cleavage is not effected with equal ease in all minerals : 
in mica, this is produced by the finger-nail ; in others, a 
slight blow in the direction of the cleavage is required, and 
some practice and skill are necessary to insure success. 
Quartz and several other minerals cleave only when heated 
and thrown into water ; other minerals do not cleave at all. 
Cleavage, when attainable, takes place parallel to some or 
all of the faces of the primary form. It is obtained with 
equal ease or difficulty parallel to similar primary faces, 
and with unequal ease or difficulty parallel to dissimilar 
primary faces, and cleavage parallel to similar planes affords 
planes of similar lustre and appearance, and the converse. 

3. Measurement of Crystals. 
^ 227. Common Goniometer.* — The angles of crystals are 

§ 226. What is cleavage in minerals? On what does it depend? Give 
examples. Is it equal in all minerals? What is the law of cleavage? 
§227. What is a goniometer? Explain the common one and its use. 

* From the Greek, gonia, an angle, and metro, I measure. 



MEASUREMENT OF CRYSTALS. 



159 





measured by means of instruments called goniometers. The 
common goniome- 
ter, v/hich is here 
figured, consists of 
a semi-circle of 
brass, graduated 
into degrees, and 
having a pair of 
steel arms moving 
on a central pivot, 
and so arranged as 
to slip in a groove 
over each other. The points a a can thus be made to embrace 
the faces of a crystal whose angle we wish to measure. When 
the edges of the sliding arms exactly fit the two faces con- 
taining the required angle, the screw which holds them 
together is tightened, and the graduated semicircle is applied 
with its centre at the poin| of intersection, when the angle is 
directly read on the arc, or -its supplement is given in the 
alternate angles. By this instrument, angles can be measured 
with only tolerable accuracy ; but where the greatest nicety 
is required, a much more delicate instrument is used, called, 

^ 228. Wollastons Rejiecting Goniometer. — The principle 
of this instrument may be understood by reference to the 
annexed figure, which represents 
a crystal (o) whose angle (a h c) is 
required. The eye at P, looking 
at the face {h c) of the crystal, 
observes a reflected image of M, 
in the direction P N. The crys- 
tal may now be so turned that 
the same image is seen reflected 
in the next face, [b «,) and in the same direction, (P N.) 
To effect this, the crystal must be turned, until a b has the 
present position of h c. The angle d b c measures, there- 
fore, the number of degrees through which the crystal must 
be turned. But d h c subtracted from 180° equals the re- 
quired angle of the crystal a b c ; consequently, the crystal 
passes through a number of degrees, which, subtracted from 
180°, gives the required angle. When the crystal is attached 




§ 228. Explain the principles of WoUaston's goniometer from the dia* 
gram. 



160 



CRYSTALLIZATION. 




jto a graduated circle, which should move with it, we have 

the goniometer of Wollaston. 
In the annexed figure, a is 
such a circle, graduated to 
half degrees, and hung by 
the axis ^, on which it moves 
with great steadiness. This 
a^is is perforated from end 
to end for the passage of a 
closely fitting rod or central 
axis, on one end of which 
is the bent joint, (c?,) carry- 
ing the crystal, (/.) By the 
head c, and the arrangement 
at J, the crystal is adjusted without moving the graduated 
wheel, and when this is accomplished in such a manner that 
|he eye of the observer placed over the crystal, as at P, 
can see a clear image of a line op the wall, (M,) or a win- 
dow-bar, in each face successively, then the graduated wheel 
(which stands when at rest at z:ero of the vernier e) is made to 
revolve, and with it the crystal, imtil the mark or window bar 
is distinctly seen in the second face. The nuniber of degrees 
and parts of a degree which correspond to the angle rer 
quired, are thus obtained directly by the movement of the 
wheel, which was beforehand placed with 180° opposite to 
the zero on the vernier. The movement of the wheel is, 
therefore, in fact, a subtraction of the angle d h c from 
180°. The great advantage of this instrument is, that we 
pan by its aid obtain very precise results, and often on crys- 
tals too small to be held in the fingers and applied to a com- 
mon goniometer. A small magnifier is sometimes attached 
to the instrument to render it more complete. 

§229. In measurements by the goniometer, a knowledge of 
the following simple principle in mathematics will be found 
pf great value. " The sum of the three angles of a triangle 
equals 180°," or ^' The suin of the angles of a polygon equals 
plaice as many right angles as the polygon has sides, less two.^^ 



How is this principle used in Wollaston's instrument. § 229. State 
the principles in this section regarding triangles and polygons. Give i^u 
example. 



ISOMORPHISM. 161 

If the figure has six sides, then it contains 2x(6 — 2)— 8 
right angles, or 8 X 90 = 720°.* 

4. Isomorphism. f 

^ 230. Identity/ of crystalline form was formerly supposed 
to indicate an identity of chemical composition. We now 
know that certain substances may replace each other in the 
constitution of compounds, without changing their crystalline 
form. This property is called isomorphism, and those bases 
which admit of mutual substitution are termed isomorphous. 
Chemistry furnishes us many examples of these isomor- 
phous bodies. Thus alumina and peroxyd of iron replace 
each other indefinitely. The carbonate of iron and carbon- 
ates of lime and magnesia are also examples, as in the com- 
mon sparry iron, [spathic iro?i,) which is a carbonate of iron, 
in which sometimes a large portion of lime crystallizes, pro- 
ducing no change of form in the mineral. Oxyd of zinc and of 
magnesia, oxyd of copper and protoxyd of iron^ also take the 
place each of the other in compounds, with no alteration of 
form. So when those bodies unite with acids to form salts, 
the resulting compounds have the same crystalline form, and 
when of the same color, are not to be distinguished from 
each other by the eye. 

In double salts, like common alum, these relations are 
also found. The sulphate of iron may take the place of 
sulphate of alumina in common alum, and no change of 
form will occur ; and soda may, in like manner, replace the 
potash. In fact, all the similar compounds of isomorphous 
bodies have a great resemblance to each other, in general 
appearance and chemical properties. The two bases in a 
double salt are, however, never taken from the same group 
of isomorphous bodies. 

^231. A knowledge of this law is of great importance to 
the chemist, and often enables him to explain, in a satisfactory 



§ 230. What is isomorphism? Name some examples. What of salts 
of isomorphous bases? Is it found in double salts? 

* The subject of crystallography cannot be further illustrated here; 
but the learner who desires to pursue it, is referred to the highly philo- 
sophical treatise on Mineralogy, by Mr. J. D. Dana, from which we 
derive the substance of the foregoing. 

t Isos, equal, and morphe, form. 



162 CHEMICAL EFFECTS OF VOLTAIC ELECTRICITY. 

iiianner, apparent coritradiciions and anomalies^ and io de- 
cide may doubtful points. It is supposed that the elements 
whose compounds are isomorphous, are also so themselves. 
A more full discussion of this subject does not belong to our 
restricted limits, and we can only mention, in conclusion, the 
group of isomorphous bodies named by Prof. Graham in his 
*' Elements." 1st Family ; Chlorine, Iodine, Bromine, Fluo- 
rine. 2d Family ; Sulphur, Selenium, Tellurium. 3d Fam- 
ily ; Phosphorus, Arsenic, Antimony. 4th Family ; Bari- 
lim^ Strontium, Lead. 5th Family ; Silver, Sodium, Potas- 
sium, Ammonium. 6th Family; Magnesium, Manganese, 
Iron, Cobalt, Nickel, Zinc, Copper, Cadmium, Aluminiumj 
Chromiunij Calcium, Hydrogen.* 

5. Vimorphism.'\ 

§ 232. Some substances have two forms, under both of 
which they are found. Thus common calc spar (carbon- 
ate of lime) is generally found in rhombohedrons, (^ 224, 
13,) but in arragonite (vi^hich is only pure carbonate of lime) 
it is seen as a rhombic prism, (^ 221, fig. 6.) 

III. CHEMICAL EFFECTS OF VOLTAIC ELECTRICITY, 

1. Electro- Chemical Decomposition, 

I 233. In discussing the electricity of chemical action, 
(^ 157,) only a passing allusion was made to the power 

231. What six families of isomorphous bodies are named? § 232. 
"What is dimorphism? §233. Why is electro-chemical decomposition 
treated in this place ? 

* M. Scheerer has lately noticed the curious and important fact, that 
in compounds containing magnesia, protoxyd of iron, and other bases of 
the 6th family above, a part of the base may be wanting without a 
change of crystalline form, provided that this be replaced by a quantity 
of water which contains three times as much oxygen as this part of thp 
base. For example, the compounds — 

Mg^Si, Mg2Si+3H and MgSi+6H, 

in accordance with this principle, are isomorphous. Thus, chrysolite and 
serpentine may be isomorphous, and much light is shed on the relations 
of hydrous and anhydrous minerals, 
t From dis, two, and morphe, forrri. 



lELeeTiio-eMEMicAL f)r:coMPositioN. 



163 



possessed by this species of electricity in producing or mod- 
ifying chemical decomposition. Having now become some- 
what familiar with the elementary constitution of matter^ 
and the laws of chemical combination, we can the more in- 
telligently proceed to a very brief review of the chemical 
effects of voltaic electricity. 

§ 234. Decomposition of W^G^er.— Water was the first 
substance on which the decomposing power of the battery 
was observed, soon after the discoveries of Galvani and 
Yolta were made known in England. When two gold 
or platinum wires are connected with the opposite ends 
of the battery, and then held a short distance asunder, in 
a cup of water, a train of gas-bubbles will be seen rising 
from each, in a distinct series, and escaping from the 
surface of the water. With an arrangement of two glass 
tubes placed over the platinum poles, as fig- 
ured in the margin, we can collect these bub- 
bles as they rise, and shall soon find that the 
gas given off from the — plate is twice the vol- 
ume of that obtained from the + plate. When 
the tubes are of the same size, this differ- 
ence of volume becomes at once evident to 
the eye. By examining these gases, (as will 
be explained in the elementary chemistry,) 
we shall find them, respectively, pure hydro- 
gen and pure oxygen, in the exact proportion 
of two volumes of the former to one of the lat- 
ter. (§ 189.) By no modification of the arrangement can we 
cause this process to vary ; the hydrogen invariably appears 
on the — side and oxygen on the -|- side. 

Water then, is not only decomposed by the voltaic cur- 
rent, but that decomposition takes place in the exact atomic 
proportions (^ 184) of the equivalents of the elements, and 
these elements seek opposite poles of the battery. 

§ 235. The experimental researches in electricity hy Mr, 
Faraday, have shed much light on this subject ; and his 
views being now generally adopted, it will be unnecessary 
for us to discuss the opinions formerly advanced by Yolta, 




§ 2.34. Mention the facts occurring in the decomposition of water. 
TIow is this made more striking? In what proportion do the erases rise ? 
Can we ciiange this proportion ? WJiat do wo infer ? § 235. What is 
gaid of Fara^a^y's researches? 



164 CHEMICAL EFFECTS OF VOLTAIC ELECTRICITY. 

Davy, and others, which are very interesting and important 
in the history ef the science, but do not now form part of 
its *' first principles." Mr. Faraday's researches required 
the introduction of certain new terms, some of which we 
will ROW explain, as we shall find them more convenient than 
any others. (].) The terminal wires or conductors of a 
battery are often termed the poles, as i^ they possessed some 
attractive power by which they draw bodies to themselves, 
as a magitet attracts iron. Mr. Faraday has shown that 
this notion is a mistake, and that the terminal wires act 
merely as a path or door to the currents, and he therefore 
calls them electrodes, from electron and odos, a way. The 
electrodes are any surfaces which convey an electric current 
into, and out of, a decomposable liquid. The term electro- 
lysis, from electron, and the Greek verb luo, to unloose, is 
used to express decomposition ; and the substances suffering 
decomposition are termed electrolytes. Thus, the experi- 
ment mentioned in the last section is a case of electrolysis, 
in which water is the electrolyte. The elements of an elec- 
trolyte are called ions, from the Greek participle, ion, going, 
since the elements ^o to the + or — electrode.* We shall 
find it very convenient to make use of the words ion, elec- 
trode, electrolysis, and electrolyte. We will now briefly 
consider the 

^ 236. Conditions of Electro-Chemical Decomposition. — 
(1.) All compounds are not electrolytes ; that is, are not di- 
rectly decomposable by the voltaic current. Many bodies, 
however, not themselves electrolytes, are decomposed by a 
secondary action. Thus, nitric acid is decomposed in the 
electrical circuit by the secondary action of the nascent 
(§ 209) hydrogen, which, uniting with one equivalent of the 
oxygen, again forms water and nitrous acid. Sulphuric 
acid is not an electrolyte, while hydrochloric acid is; 
and the nascent chlorine from the latter attracts the + elec- 
trode, if it be of gold. (2.) Electrolysis cannot happen un- 

What did they require ? What does he call the poles, and why ? Ex- 
plain the terms electrode, electrolysis, and electrolyte. What are ions? 
§ 236. Are all compounds electrolytes? Give examples. 

* Mr Faraday further distinguishes the electrodes, as the anode and 
the cathode, from ana, upwards, and odos, way, or the way in which the 
sun rises ; and kata, downwards, and odos, or the way in which the sun 
sets ; the anode is -|- and the cathode — . 



ELECTRO-CHEMICAL DECOMPOSITION. 1G5 

less the fluid be a conductor of electricity ; and no solid 
body, however good a conductor, has ever been thus decom- 
posed. A plate of ice, hov^ever thin, interposed between 
the electrodes, will entirely prevent the passage of the power ; 
but the electrolysis will proceed as soon as the least hole 
melts in the ice, through which the power can pass. Fluidity 
is therefore a very essential condition of electrolysis. The 
fluidity may be that of heat, or of solution ; thus, the chlorids 
of lead, silver, and tin, are not electrolysed in a solid state, 
but when fused they are decomposed with ease. (3.) The 
ease of electro-chemical decomposition seems in a good de- 
gree proportioned to the conducting power of the fluid. Thus, 
pure water is by no means a good conductor, and its electroly- 
sis is difficult ; but the addition to it of a ^ew drops of sulphu- 
ric acid, or of some other soluble conductor, greatly pro- 
motes the ease with which it is decomposed. (4.) The 
amount of electrolysis is directly proportioned to the quan- 
tity of electricity which passes the electrodes. (5.) The 
binary compounds of the elements (§ 193) as a class are the 
best electrolytes. Water and iodid of potassium are in- 
stances. While sulphuric acid, which has 3 equivalents of 
base to one of acid, is not an electrolyte. No two elements 
seem capable of forming more than one electrolyte. Most 
of the salts are resolvable into acid and base. Thus, sul- 
phate of soda is resolved into sulphuric acid, which appears 
at the + electrode, and will there redden a vegetable blue ; 
and the soda which appears at the — electrode will re- 
store the previously reddened blue ; so that by reversing the 
direction of the' current, these striking effects are also re- 
versed. 

^ 237. (6.) A single ion, as bromine, for instance, has 
no disposition to pass to either of the electrodes, and the 
current has no effect upon it. There can be no electrolysis 
except v/hen a separation of ions takes place, and the sep- 
arated elements go one to each electrode. (7.) There is no 
such thing in fact, (as has been often supposed,) as an 
actual transfer of ions from one part of the fluid to either 



What is the second condition of electrolysis ? Give examples. (3.) 
To what is the ease of electrolysis proportioned? (4) To what is its 
amount owing? (5.) What class of compounds are the best electrolytes ? 
(jive examples. What of salts? Give examples. §2,37. (6.) Wiiat is 
said of a single ion ? (7.) Wli^tof the transfer Qf iop.s? 



166 



CHEMICAL EFFECTS OF VOLTAIC ELECTRICITY. 



electrode. In the case of water, for example, (^ 234,) oxy- 
gen is given out on one side and hydrogen on the other. 
In order that this may be the case, there must be water be- 
tween the electrodes. We cannot believe that the separa- 
tion of the elements takes place at the electrode where 
one element is evolved, and that the other travels over 

unseen to the opposite elec- 
trode. We may, however, 
conceive of water in its quiet 
state, as represented by the an- 
nexed diagram, each molecule 
being firmly united by polar attractions (§ 217) to every 
other, and that the electrolytic force of the electric current 
has power to disturb this polar equilibrium, each molecule 
being similarly affected. In this case the electrolysis will 
proceed from particle to particle through the whole chain 
of affinities, decomposing and recomposing, until the ultimate 
^-^ ^-^ ^.^ ^_. ^-.^ ^^ particle on each side, hav- 

(2)f®l©l@l©l©l@ 






@j@@J@)@@J® 



ing no polar force to neu- 
tralize it, escapes at that 
electrode which has a po- 
larity opposite to itself. 
This explanation may be better understood, perhaps, by in- 
specting the second diagram, which represents a series of 
compound molecules of water undergoing electrolysis, tjie 
HO being eliminated at the opposite extremities. The 
same explanation will be found to serve for ail other cases 
of electrolysis, both simple and secondary. 

§ 238. (8.) A surface of water, and even of air, has, by 
Faraday's researches, been shown capable of acting as an 
electrode, proving that the contact of a metailic conductor v/ith 
the decomposing fluid is not essential. The discharge from 
a powerful electrical machine (152) was made to pass from a 
sharp poiiit through air to a pointed piece of litmus paper 
moistened wilh Bulphate of soda, and then to a second piece 
of turmeric paper similarly moistened. This discharge had 
power to effect a true electrolysis ; the blue litmus was red- 
dened by the sulphuric acid set free from the sulphate of 



Give the explanation offered of the decomposition of water. § 238. 
(8.) What is said of electrolysis without metallic conductors? Explain 
the ^xperircent of the electrolysis of sulphate of soda by the electrical 



ELECTRO-CHEMICAL DECOMPOSITION. 167 

soda, while the yellow turmeric was turned brown by the 
alkaline soda from the same salt. 

^ 239. (9.) Electrolysis takes place in a series of compounds 
in the precise order of their equivalents. Thus if wine-glasses 
are arranged in a series, and in one is placed sulphate of 
soda, in another acidulated water, in another iodid of 
potassium, and in another hydrochloric acid, and if the whole 
series be connected together by siphon tubes, or moistened 
lampwick, passing from glass to glass, and then a powerful 
current of electricity be passed through them, electrolysis 
will occur in all, but not in an equal degree. 

It has been proved by accurate experiment that the 
decomposition which ensues is in exact proportion to the 
equivalents of each substance. In other words, we may say, 
it requires one equivalent of electricity to decompose one 
equivalent of an electrolyte, formed from the union of an 
equivalent of acid and another of base. Conversely, from 
the fact that an equivalent of electricity is required to de- 
compose any compound, it is proved that the opposite 
elements of this compound, in uniting, will disengage the same 
equivalent of electricity. 

^ 240. (10.) The passage of a current within the cells of a 
voltaic battery (161) depends also upon the decomposition 
in each cell, equally with that between the platinum elec- 
trodes. The same phenomena which we notice in the de- 
composing cell (^ 234) take place also in each battery cell. 
Water is decomposed, and the hydrogen is given off from 
the positive plate, while the oxygen combines with the zinc, 
and thus escapes detection. Therefore, no fluid not an 
electrolyte is suitable to excite a battery. Acid water acts, 
for this purpose, only by the decomposition of the water, 
and oxydation of the zinc. The presence of the acid is 
useful only so far as it combines with the oxyd of zinc 
constantly accumulating on the zinc plate, which must be 
removed as fast as formed, in order to keep up a steady 
flow of electricity. 



§ 239. How does electrolysis occnr in a series of compounds? In 
other words, what do we say ? Conversely, what ? § 240. How does a 
current pass in the cells of a battery? What happens in each cell? 
Therefore what ? How does acid-water act in the battery ? 



168 CHEMICAL EiTECTS OF VOLTAIC ELECTRICITY^ 



If 



/ N K 




p6 



§ 241. From wLat has been said, we can see that a de- 
(b) composing cell inter- 

posed in the circuit 
will give us an exact 
account of the amount 
y of electricity flowing. 
Such an instrument 
has been called by 
Faraday a voltameter, 
(measurer of voltaic 
electricity,) and is fig- 
tired in the iliargin {a.) 
It differs from the de- 
composing cell,(^ 234,) 

in being a single cell, and having a ground 
glass lube at top bent twice, so as to deliver 
the accumulating gases into a graduated air- 
vessel, in which this volume is measured. 
A more simple form of the apparatus is easily 
constructed, as shown in 5, which is a short 
piece of glass tube, with two corks and a bent tube, {t ;) 
The electrodes pp pass through the corks, and should termi- 
nate in broad plates of platinum foil. A 
common form of the instrument is seen 
in the annexed figure, which has only 
one tube, and that is graduated. When 
this is filled with the mixed gases, and 
a lighted match is applied to the open 
end, the two elements tmite again, with 
a loud explosion, and vivid flash. If 
the apparatus is so arranged that this 
can be done over water without access 
of air, the fluid rushes up to fill the 
vacuum occasioned by the re-union of 
the elements in the formation of wa^ 
ter. 

^ 242. The theories which have been 
proposed to account for electro-chemical 
decomposition and the action of the vol- 
taic circuit, we cannot discuss here, any further than to 




§241. What is a voltameter? What does it show? Explain the 
figures. When the mixed gases are fired, what happens? 



SUSTAINING BATTERIES. 



1G9 




say, that the clieinical theory, first proposed by Dr. Wollaston, 
is now generally accepted. Yolla argued that the contact 
of different metals was essential to the production of a cur- 
rent. The researches of Faraday, however, in confirnri- 
ing the chemical view of Wollaston, have completely dis- 
proved the contact theory. A very simple experiment by 
Faraday illustrates this statement. A slip of sheet zinc 
bent at a right angle is hung in a glass of dilute 
acid ; on it is laid a folded piece of bibulous paper 
moistened with iodid of potassium. A platinum 
plate, with an attached wire of the same metal, is 
now placed in the acid water, but not in contact 
with the zinc ; the sharpened end of the wire is 
bent, so as to touch the moistened paper, and very 
Boon it is discolored by a brown spot made by 
the free iodine, liberated from the electro-chemi- 
cal decomposition of the iodid of potassium, with 
which the paper is moistened. There is no contact of met- 
als, and the current is excited only from the decomposition of 
the iodid out of the cell, and of the water in it. A very 
strong argument in favor of the chemical theory has been be- 
fore mentioned, (160,) that the direction of the current is 
always determined by the nature of the chemical action — the 
metals most' acted on being always positive. Professor 
Berzelius, in view of the facts of electricity, considers all 
chemical action as the result of opposite electrical states in 
the elements and their compounds. 

We have now made all the explanations that are neces- 
sary to enable us to understand the principles and construc- 
tion of 

2. Sustaining Batteries. 

§ 243. Local action, — In the old forms of batteries made 
of copper and zinc unamalgamated, (163,) there is always a 
great amount of local action in each cell, arising from the 
impurity of the zinc. We have before explained how, by 
amalgamating the zinc with mercury, it is reduced to a state 
of electrical uniformity, (^ 160, note.) In order to have a 
constant voltaic current of equal power, not only the evils 
arising from local action must be avoided, but also, in some 



§ 242. What two theories have been proposed to account for the elec- 
trical phenomena of electrolysis? What simple experiment disproves the 
contact theory? § 243. What are sustaining butteries ? 

35 



170 



CHEMICAL EFFECTS OF VOLTAIC ELECTRICITY. 



r 



degree, the weakening of the acid solution. Batteries so 
constructed as to meet these difficulties, are called sustain- 
ing batteries, or constant batteries. We will first mention 

^ 244. DanielVs Constant Batter 7/. —This truly philo-. 
sophical instrument (a vertical section of which is annexed) 
is made up of an exterior circular cell of copper, ( + ) three 
and a half inches in diameter, which serves 
both as a containing vessel and as a nega- 
"» tive element ; a porous cylindrical cup of 
earthen-ware, (P, fig. b,) (or the membrane 
of an ox-gullet,) is placed within the copper 
cell, and a solid cylinder of amalgamated 
zinc( — z) within the porous cup. The outer 
cell (c) is charged by a mixture of eight 
parts of vi^ater and one of oil of vitriol, satu- 
rated with blue vitriol, (sulphate of cop- 
per.) Some of the solid sulphate is also 
suspended on a perforated shelf, or in a 
gauze bag, to keep up the saturation. The 
inner cell is filled with the same acid 
water, but without the copper salt. Any 
number of cells so arranged are easily con- 
nected together by binding screws, as in the figure — -the c of 



one pair to the 2 of the next, and so on. This instrument, when 



arranged and charged as here described, will 
give out no gas. The hydrogen from the de- 
composed water is not given off in bubbles on 
the copper side, as in all forms of the simple 
circuit of zinc and copper ; because the sul- 
phate of copper there present is decomposed by 
the circuit, atom for atom, with the decomposed 
water, and the hydrogen takes the atom of oxyd 
of copper, appropriating its oxygen to form water 
again, and metallic copper is deposited on the 
outer cell. No action of any sort results in 
this battery, when properly arranged, until the 
poles are joined. Ten or twelve such cells 
form the most active, constant, and least costly, 
but not the least troublesome battery which can 




be procured. 



§ 244. Explain Daniell's Battery from the figure. AVhat is its principle 
of action? Wiiat becomes of the hvdrogen? When does this battery- 
act? 



SUSTAIxVING BATTERIES. 



171 




§> 245. Grove's Battery. — Professor Grove, of London, has 
contrived another compound sustaining battery, of great pow- 
er, and nnost remarkable intensity of action. The 
metals used are platinum and amalgamated zinc. 
A vertical section of this battery is shown in the 
annexed figure. The platinum ( + ) is placed 
in a porous cell of earthen-ware, containing 
strong nitric acid. This is surrounded by the 
amalgamated zinc ( — ) in an outer vessel of 
pretty strong sulphuric-acid-water, (six to ten 
parts water to one of acid, by measure.) The pla- 
tinum, being the most costly metal, is here sur- 
rounded by the zinc, in order to economize the 
power as much as possible. In this battery 
the hydrogen of the decomposed water on the zinc side 
enters the nitric-acid cell, decomposes an equivalent of 
the acid, forming water with one equivalent of its oxygen, 
while the deutoxyd of nitrogen is given out as a gas, and com- 
ing in contact with the air, this gas is converted into nitrous- 
acid fum.es. No other form of battery can be compared with 
this for intensity of action. A series of four cells (the platinum 
foil being only three inches long and half an inch wide) 
•will decompose water with great rapidity ; and twenty such 
cells will evolve a very splendid arch of light from points of 
prepared charcoal, and deflagrate all the metals very power- 
fully. It is rather costly, and troublesome to manage, as are 
all batteries with double cells and porous cups. The author 
has contrived a very efficient form of the same battery, in 
which mineral carbon (plumbago) is substituted for the pla- 
tinum.* But all other batteries yield in simplicity and ease of 
management to that contrived by Mr. Sm.ee, and known as 

^ 246. Smee^s Battery. — It is formed of zinc and silver, 
and needs but one cell and one fluid to excite it. The 
silver plate (S) is prepared by coating its surface with 
platinum, thrown down on it by a voltaic current, in the 
state of fine division, which is known as platinum-black. 
The object of this is to prevent the adhesion of the liberated 



§245. What is Grove's Battery? How does it diifer from the last? 



How does it act? 
tery ? 



What is its energy? §246. AVhat is Smee's Bat- 



* American Journal of Science, (1st series,) vol. xliii, p 393. 



172 



CHEMICAL EFFECTS OF VOLTAIC ELECTRICITY. 



hydrogen to the polished silver. Any polished smooth surface 
of metal will hold bubbles of gas with great obstinacy, thus 
preventing in a measure the contact of the 
fluid and the plate by the interposition of a 
film of air-bubbles. The roughened sur- 
face produced from the deposit of platinum- 
black entirely prevents this. The zinc 
plates (z z) in this battery are well amalga- 
mated, and face both sides of the silver. 
The three plates are held in position by a 
clamp at top, (d), and the interposition of a 
bar of dry wood (w) prevents the passage of 
I a current from plate to plate. Water, 
acidulated with one-seventh its bulk of oil 
of vitriol, or, for less activity, with one- 
sixteenth, is the exciting fluid. The quantity/ of electricity 
excited in this battery is very great, but the intensity is 
not as great as in those compound batteries just described, 
where there is a double electrolysis, and of course a double 
amount of intensity, acquired. This battery is perfectly 
constant, does not act until the poles are joined, and, with 
no attention, will maintain a uniform flow of power for 
days together. A plate of lead, well silvered, and then 
coated with platinum-black, will answer equally as well, 
and indeed better than a thin plate of pure silver. This 
battery is recommended over every other for the student, as 
comprising the great requisites of power, cheapness, ease 





of management, and constancy. A form of it, well calculated 
for the student's laboratory, is here shown, which is a porcelain 

How is the silver plate prepared? What is the use of the platinnm- 
black? How is this battery excited? What acts as well as silver? 
What recommends this battery over others? 



ELECTRO-METALLURGY. 173 

trough with many cells. This battery is the one universally 
employed in electro-metallurgy. 

3. Electro-metallurgy , 

§ 247. The depositing of metals by electrical agency 
seems to hav^e been suggested by Daniell's battery. It has 
been remarked, that the copper of the sulphate of copper in 
the outer cell of that battery was deposited in a metallic state. 
The procuring of a pure metal in a perfectly malleable state, 
by means of a current of electricity, is a most important fact, 
and has given rise to a new and valuable art, which is every 
day extending its applications. We thus accomplish in fact 
a cold Casting of copper, silver, gold, zinc, and many other 
metals ; and a new field of great extent 
has been thus opened for the application of 
metallurgic processes. The only and very 
simple apparatus required to show these re- 
sults experimentally, is represented in the 
annexed figure. It is nothing, in fact, but a 
single cell of Daniell's battery. A glass 
tumbler, (S,) a common lamp-chimney, (P,) 
with a bladder-skin tied over the lower 
end and filled with dilute acid, is all the ap- 
paratus required. A strong solution of sul- 
phate of copper is put in the tumbler, (S,) 
and a zinc rod ( Z ) in P ; the moulds, or casts, (m, m,) are seen 
suspended by wires attached to the binding screv/ of Z. Thus 
arranged, the copper solution is slowly decomposed, and the 
metallic copper is evenly and firmly deposited on m, m. 
A perfect reverse copy of m is thus obtained in solid malle- 
able copper. The back of m is protected by varnish, to pre- 
vent the adhesion of the metallic copper to it. In this 
manner the most elaborate and costly medals are easily mul- 
tiplied and in the most faithful manner. In practice, casts 
are made in fusible metal of the object to be copied, and 
the operation is conducted in a separate cell, containing 
only the sulphate of copper, one of Smee's batteries sup- 
plying the power. The art is also now equally applied 
to plating in gold and silver from their solutions, the metals 

§247. What first suggested electro-metallurgy? What is required in 
order to obtain several medals in the metallic state? Explain the process 
for obtaining the copy of a medal. 

15* 




174 CHEMICAL EFFECTS OF VOLTAIC ELECTRICITY. 

thus deposited adhering perfectly to the metallic surface on 
which they are deposited, provided these be quite clean 
and bright. Many details in these processes, very needful 
to the successful practice of the art, are necessarily omitted 
here.* But we must not suffer ourselves to be led away 
from our strict adherence to the '^ First Principles of Chem- 
ical Philosophy," by the instructive and entertaining results 
to which the application of these principles has led. 

248. We have now finished our preliminary view of those 
great powers of nature, whose operations we see to a 
greater or less extent in every chemical process. It may be 
thought that we have devoted too large a space to the topics 
already discussed ; but the author is convinced, from 
long observation, that if the principles of chemical philos- 
ophy are well acquired by the student, but little difficulty 
will be experienced in afterwards pursuing, even alone, 
and without the aid of a teacher, the wide detail of ele- 
mentary chemistry. In entering on the execution of the 
remaining portion of our task, it is with the full understand- 
ing that no attempt is made on our part at presenting even a 
complete outline of the countless facts of elementary chemistry. 
Only such selections will be made from them as are deemed 
most in point to illustrate and enforce the principles al- 
ready laid down, and to increase our familiarity with the 
philosophy of chemistry. It is hoped that this course will 
be satisfactory to both teacher and pupil, and the apology 
implied in this remark is intended to explain any appa- 
rent deficiencies which may be seen on the succeeding 
pages. The complete and philosophical treatises of Turner, 
Kane, and Graham, are all excellent works of reference 
for the more advanced student. 

§ 248. What is said of the importance of chemical philosophy? 

* The reader is referred for further information to Mr. Smee's excel- 
lent " Elements of Electro-Metallurgy," or Walker's " Electrotype Man- 
ipulation," re-published at Philadelphia. 



CHLORINE. 183 

limpid fluid of a fine yellow color, which does not freeze at 
zero, and is not a conductor of electricity. It immediately 
returns to the gaseous state with effervescence on removing 
the pressure. 

Water recently boiled will absorb, if cold, about twice its 
bulk of chlorine gas, assuming its color and characteristic 
properties. The moist gas exposed to a cold of 32°, or 
more, will solidify in beautiful yellow crystals, which are a 
definite compound of one equivalent of chlorine and ten of 
water, (C110HO=r35-41 +90.) If these crystals are sealed 
up (hermetically) in a glass tube, they will, on melting, ex- 
ert such a pressure as to liquefy a portion of the gas, which 
is distinctly seen as a yellow fluid not mis'cible with the 
water which is present. Chlorine is one of the heaviest 
of the gases, its density being 2*47, and 100 cubic inches 
weighing 76-5 grains. 

§ 261. Its bleaching power is its most remarkable property, 
and a most valuable one in the arts, in bleaching rags for paper, 
and in whitening linen and cotton goods. For these purposes, 
it is procured in large quantities by the action of oil of vitriol 
on a mixture of common salt and manganese. Either the gas 
is used directly, or its solution in water, or its compound 
with quicklime, known as " bleachingpowders." It is easy to 
see its power in discharging colors, by bleaching some scraps 
of calico and common writing on paper, in a wine-glass, by 
the solution of the gas in water. Dry chlorine does not 
bleach, moisture being essential to this process. 

^ 262. The 'disinfection of offensive apartments, sewers, 
and other like places, is rapidly accomplished by chlorine, and 
no other substance is in this respect equal to it ; but care is 
required not to use too much of it in apartments which are 
inhabited. The bleaching powder mixed in shallow vessels 
with water is sufficient for most purposes of this nature. 

^263. Double Condition, or Allotropism of Chlorine. — 
Chlorine can exist in two states, — an active and a passive 
state. The first is its condition as ordinarily known, when 
prepared in day-light. If an aqueous solution of chlorine 

How does cold water affect it? When moist chlorine is cooled, what 
happens? What is the density of chlorine, and weight of 100 cubic 
inches? §2G1. What is its most remarkable property ? How is it used 
for this purpose? Does dry chlorine bleach? § 2G2. Hqw does it j^tTeet 
badodara? 



1^4 NON-METALL'K^ ELEMENTS. 

be prepared as before mentioned, in recently boiled water, 
and a part of it be expf)sed in €gi inverted bulb, to the direct 
rays of the sun, or a strong day-light ; while another por- 
tion as soon as prepared is set aside in a dark closet, and 
in a similar vessel, we shall find them very differently affect- 
ed. That which*%vas in the ^ark will have undergone no 
change, while that in the sun-light will have suffered 
decomposition, a notable quantity of nearly pure oxygen 
will have collected in the bulb, as shown in the an- 
nexed figure, and hydrochloric acid will have been form- 
ed in the fluid from the union of the chlorine and the 
hydrogen of the water, whose oxygen is set free. The 
rapidity-^)f this decomposition of water by the chlo- 
rine depends on the quantity of the sun's rays and the tem- 
perature, and being once begun, it continues afterwards even 
in the dark. Mere increase of temperature does not, alone, 
cause the decomposition, although it aids it. Some tim.e 
elapses after the chlorine water is exposed, before it begins 
to be decomposed, during which the chlorine is undergoing its 
specific change. The indigo rays (^ 65) are chiefly instru- 
mental in producing this effect, and impart to chlorine an 
activity which it does not possess when kept in the dark. 
The relations of chlorine to light are very interesting and 
important, and we shall have something more to say about 
them under hydrogen.* Chlorine, as we shall see, is not 
the only element which is known to us in a double con- 
dition. 

Compounds of Chlorine with Oxij^ren. 

§ 264. Chlorine has comparatively little affinity for oxy- 
gen, being too closely allied to it in general properties to 
form very stable combinations with it. Its strongest affinity is 
for hydrogen and the metals. A lighted candle will burn 
with an enlarged flame in a vessel of chlorine, and an 
abundant cloud of black smoke is given off, being the car- 
bon of the flame, which cannot burn in chlorine. A rag or bit 

§ 263. Explain what is said of the double condition of chlorine, and 
the effect of light on it. § 264. How are chlorine and oxygen affected 
to each other ? 

* This subject has been ably discussed in a recent paper by Dr. J. W. 
Draper. Am. Jour. Science, vol. xlix, (1st series,) p. 346. 



CHLORINIi. 



185 



of paper wet in oil of turpentine, and held in the mouth of a 
bottle of chlorine, is inflamed, while the interior of the vessel 
is coated with a brilliant black varnish of carbon derived from 
the oil. In these cases the chlorine combines with the hydro- 
gen of the combustible body, and not with the carbon. 
Powdered metallic arsenic, antimony, and some other metals, 
are inflamed in chlorine gas, being converted into chlorids. 
Phosphorus is also spontaneously inflamed in chlorine, burn- 
ing with a pale yellowish-white light. The strong afhnity 
of chlorine for hydrogen is shown (^ 263) by its power of de- 
composing water in the sun's light. The bleaching power of 
chlorine is due probably to its aflinity for hydrogen. Print- 
ers' ink, of which carbon is the basis, is not decolorized by- 
chlorine. 

§ 265. Chlorine unites with oxygen^ only by circuitous 
means, and forms with it four compounds, as follows : 

Composition by Weight. 





Symbol. 


Chlorine. 


Oxygen. 


Hypochlorous acid, 


CIO 


35-41 


8 


Chlorous acid. 


CIO, 


35-41 


32 


Chloric acid. 


CIO, 


3541 


40 


Hyperchloric acid, 


CIO, 


35-41 


56 



^266. HyperchLorous Acid, (Euchlorine.) — This body 
is always formed when chlorate of potash is acted on by 
hydrochloric acid, but is almost instantly resolved into 
chlorous acid and 
chlorine, when thus 
produced. To. pro- 
cure it, the best 
way is to pass a 
gentle stream of dry 
chlorine gas over 
red precipitate, (the 
oxyd of mercury 
prepared by precip- 
itation,) contained 
in an apparatus 
similar to the annexed fioure. 

o 

How does chlorine affect bnrninjT bodies, as a caudle? Why is tur- 
pentine inflamed in it? How does it affect other bodies? § 2(i5. Name 
the compounds of oxygen and chlorine, and their constitution. § 266. 
How is hyperchlorous acid formed? Explain the apparatus. 

16* 




)i86 NON-METALLIC ELEMENTS. 

the gas-bottle, (/;,) and passes by a bent tube to a long hori- 
zontal tube (t) filled with the red precipitate, with w^hich it 
forms chlorid of mercury, w^hich remains in the tube, while 
hyperchlorous acid (CIO) is evolved as a gas, and is collect- 
ed in a by displacement of air. 

^ 267. This gas is of a yellowish-green color, much re- 
sembling chlorine ; water rapidly absorbs 100 times its own 
volume of it. It is easily exploded by heat, oxygen and 
chlorine being the result. At zero it is condensed into a 
deep red liquid, which is slowly dissolved by water. It 
acts more corrosively on the skin than nitric acid, and bleach- 
es powerfully. Its aqueous solution is very unstable, being 
decomposed by light, and even by agitation with irregular 
bodies, as broken glass. Hypochlorous acid is one of the 
most powerful oxydizing agents known, especially in raising 
sulphur and phosphorus to their highest state of oxydation, 
a result which only strong nitric acid can accomplish. The 
*' euchlorine^^ of Davy is a mixture of chlorine and chlorous 
acid, and not a protoxyd of chlorine, as was supposed. 

§268, Chlorous acid, ClO^. — This body is obtained by 
the action of hydrochloric acid on chlorate of potash. For 
this purpose, a little of the salt, in a small glass retort, 
is covered with diluted sulphuric acid, (1 acid and 4 water, 
cooled,) or with its bulk of hydrochloric acid, and gently 
heated by a warm water bath. A deep yellow gas is evolv- 
ed, w^hich may be collected like chlorine, by displacement 
of air in dry vessels. It is exceedingly explosive, and will not 
bear the heat of boiling water without being forcibly resolved 
into its elements. A rag wet with oil of turpentine at once 
explodes it. It is composed by volume (§ 189) of tv^o vol- 
umes of chlorine and four volumes of oxygen condensed 
into four volumes. It is largely dissolved in water, forming 
a rich yellow solution with bleaching properties. It forms 
a series of salts with the alkalies, and is capable of com- 
pression into a liquid. 

§ 269. If strong sulphuric acid is poured upon a small 
quantity of crystals of chlorate of potash in a wine-glass, a 
violent crackling is heard, and the glass is soon filled with the 



§ 267. What are the properties of this gas ? How does its aqueous 
solution behave? Has it bleaching properties? How are its oxydizing 
powers? §268. How is chlorous acid obtained? Describe its proper- 
ties. How does it affect combustibles ? How does heat affect it ? 



IBROMINE. 187 

heavy yellow vapors of the chlorous acid gas, which at once 
inflames a rag held over it wet with turpentine, with a 
smart explosion. If the chlorate of potash be mixed with su- 
gar, a drop of sulphuric acid will inflame the mixture with a 
brilliant combustion. Phosphorus burns in this gas sponta- 
neously, and occasions an explosion. If some small fragments 
of phosphorus are added to a glass of water at the bottom of 
which a few crystals of chlorate of potash have been pla- 
ced, and sulphuric acid is introduced by means of a long- 
tubed funnel to the bottom of the vessel, the salt is decom- 
posed, and the phosphorus flashes under water, in the chlo- 
rous acid which is set at liberty. 

§ 270. Chloric acid, CiO^, is the most important com- 
pound of chlorine and oxygen. It is formed by passing 
chlorine gas through a solution of pure potash, to satur- 
ation ; on evaporating this solution, flat tabular crystals 
of a white salt are gradually formed, which are chlorate of 
potassa w^hile a chlorid of potassium remains in the solu- 
tion. This important salt, as already mentioned, (^ 252,) 
is a compound of chloric acid and potassa, (ClO^KO.) 
The acid is obtained separate and pure with some difficulty, 
by decomposing a solution of chlorate of baryta by the re- 
quisite amount of sulphuric acid, and gradually evaporating 
the liquid to a syrup. In this state its affinity for all com- 
bustible matter is so great, that it cannot be kept for an instant 
in contact with any substance containing carbon or hydro- 
gen. The chlorates are at once recognized by their pow^er- 
ful action on combustible matter, by yielding pure oxygen 
when heated, a*nd by giving out the yellow chlorous acid 
when treated w^ith sulphuric acid. 

III. BROMINE. 

Equivalent, 78 26. Symbol, Br. Density, in vapor, 5*93. 

§ 271 . History, This element was discovered in 1826, by 
M. Balard, in the mother-liquor, or residue of the evaporation 

§ 269. What happens when chlorate of potash is treated with strong 
Bulphuric acid? How is the combustion of phosphorus shown by it 
under water? § 270. Describe the formation of chloric acid. What use 
has already been made by us of its compound with potash ? AVhat are 
its characteristic properties? § 271. When, where, and_by whom, was 
bromine discovered? 



188 NON-METALLIC ELEMENTS. 

of sea-water. It is named, from its offensive odor, [hromos, 
bad odor.) In nature it is found in sea-water combined with 
alkaline bases, and in the waters of many saline springs and 
inland seas. The salt springs of Ohio abound in the com- 
pounds of bromine, and it is found in the waters of the Dead 
Sea. The only use which has been made of bromine in 
the arts is in the practice of photography. It is also used 
in medicine. In a chemical point of view it is Very inter- 
esting, from its similarity in properties, and the parallelism 
of its compounds to chlorine and iodine, 

§ 272. Preparation.— T\\Q mother-liquor containing bro- 
niids, is treated with a current of chlorine gas, which de- 
composes these salts, setting the bromine free, which at once 
colors the liquid of a reddish-brown color. Ether is added 
and shaken with the liquid, until all the bromine is taken 
up by the ether, which acquires a fine red color, and sepa- 
rates from the other fluids. Solution of caustic potash is 
then added to the ethereal solution, forming bromid of potas- 
sium and bromate of potash. This solution is evaporated to 
dryness, and the salts being collected are heated in a glass 
retort with sulphuric acid and a little oxyd of manganese. 
The bromine distills over, (117,) and is condensed in a 
cooled receiver, into a red fluid. 

§ 273. Properties, — Bromine somewhat resembles chlorine 
in its odor, but is more offensive. At common temperatures it 
is a very volatile liquid, of a deep red color, and with a spe- 
cific gravity of 3, being one of the heaviest fluids known. 
Sulphuric acid floats on its surface, and is used to prevent 
its escape. At zero it freezes into a brittle solid. A few 
drops in a large flask will fill the whole vessel when slightly 
warmed, with blood-red vapors, which have a density of 
nearly 600. It is a non-conductor of electricity, and suffers 
no change of properties from heat or any other of the im" 
ponderable agents. It dissolves slightly in water, forming 
a bleaching solution. 

Bromine unites with oxygen, forming hromic acid, (BrO^,) 
which is similar in all its actions to chloric acid. It forms 
salts — bromates — with alkaline bases. 



Whence its name ? How is it found in nature? What use is made of it? 
§272. Describe its preparation. § 273. Describe its properties. How 
does it resemble chlorine ? § 274. How is iodine found associated ? Who 
idiscov^jed it^ ajjd when? What are its uses ? Does it unite with oxjgeii ? 



IODINE. 189 

IV. IODINE, 

Equivalent, 126 36. Symbol, I. Density in vapor, 8*707. 

^ 274. History. — Like chlorine and bromine, this sub- 
stance has its origin in the sea, being secreted by nearly 
all sea-weeds from the waters of the ocean. It was 
discovered in 1811, by M. Courtois, of Paris, in the kelp, 
or ashes of sea-weeds. The common * bladder sea-weed,' 
(fucus vesiculosus,) and many other sea-weeds of our 
own coasts, abound in salts of iodine. It has been found 
in mineral springs rather abundantly, and in one or two 
minerals. In the arts its chief uses are for the photographic 
pictures, and lately it has been employed in France in the 
process of dyeing. In medicine it is of great value in gland- 
ular and other diseases. 

§ 275. Preparation. — Kelp is treated with water, which 
washes out all the soluble salts, and the filtered solution 
is evaporated until nearly all the carbonate of soda and 
other saline matters from sea-water have crystallized 
out. The remaining liquor, which contains the iodine, is 
mixed with successive portions of sulphuric acid in a leaden 
retort, and after standing some days to allow the sulphureted 
hydrogen, &c. to escape ; peroxyd of manganese is added, 
and the whole gently heated. Iodine in a purple cloud dis- 
tills over and is condensed in a receiver, or series of two- 
necked-globes. 

§ 276. Properties. — Iodine crystallizes in brilliant blue- 
black scales of a metallic lustre, and somewhat resembles 
plumbago. When slowly cooled from a state of dense 
vapor in a glass tube hermetically sealed, it will crystallize 
in acute octahedrons with a rhombic base, (^ 221.) The 
density of iodine is pf'948, ( water rr:l,) it melts at 225^ and 
boils at 247"^, forming a superb violet vapor of unequaled 
beauty ; (hence its name, iodes, like a violet.) For this 
purpose a iew grains of it may be volatilized in a bolt-head, 
(74,) or on a piece of heated brick. If a small portion is 
thrown into a red-hot platinum crucible, it at once assumes the 

§ 275. How is it prepared ? § 276. Describe its properties ? How 
does it crystallize? Give its density in vapor, and as a solid its point of 
fusion. In what is it soluble ? By what easy test is it detected? § 277. 
What compound does it form with oxygen 1 



190 NON-METALLIC ELEMENTS. 

spheroidal state ( 1 35) and will roll about in a liquid globule and 
give off very little vapor. If the crucible is now allowed to 
cool to about 220°, it suddenly bursts into a cloud of purple 
vapor, forming a most striking, easy and instructive experi- 
ment. 

Iodine is almost insoluble in pure water, requiring 7000 
parts of water to dissolve one of iodine, (one grain to a gal- 
lon of water.) Alcohol and ether dissolve it freely, and so 
do solutions of nitrate or hydrochlorate of ammonia, and of 
iodids. It stains the skin temporarily deep brown, and its 
odor reminds us of chlorine, but it is much less annoying. 

Iodine forms a deep blue compound with a cold solution of 
common starch, by which it may at once be detected, this 
being a characteristic test. In combination, it may be 
delected by the same agent, if a little nitric acid or chlorine 
water is previously added to the fluid supposed to contain an 
iodid, whereby the iodine is set free. 

Compounds of Iodine with the oxygen group, 

^ 277. Iodine unites with oxi^gen, forming iodic and h^" 
periodic acids. Their constitution is seen in the following 
formula^.. 

SjmboJ. Composition by weight, 

lo^ne. Osygen. 

Iodic acid, 10^ 126-36 40 

Hyperiodic acid, 10^ 126-36 56 

These acids are analogous to the chloric and perchloric 
acids, and the similar acids of bromine. Iodic acid is 
formed by the action of strong nitric acid on iodine, and sub- 
sequent evaporation, to expel the free nitric acid remaining. 
It is a rery soluble substance, and crystallizes in six-sided 
tables. 

§ 278. Both bromine and iodine combine with energetic 
combustion or explosive violence wifh phosphorus, and seve- 
ral of the metals, forming brom/ids and iodids with such bases. 
Chlorine unites with iodine, forming two, and possibly three 
distinct chlorids, (ICl, ICl^, and ICl^.) These are formed 



Give their composition and formuloe. To what are these acids anal- 
ogous? What are the compounds of iodine and oxygeB? §278. 
How are bromine and iodine affected by phosphorus and the metals? 
Does chlorine unite with iodine ? 



FLUORINE. 191 

by the direct action of chlorine on dry iodine. There are 
also bromids of iodine of uncertain composition. 



V. FLUORINE. 

Equivalent^ 18'70. Symbol, F. Density, 1-289. 

^ 279. History and Properties. — This element has only very 
lately been obtained in a free state, although We have long 
known its compounds- Its remarkable energy of combina- 
tion with the metaJs, and especially with silicon, which 
is a constituent of all glass, has rendered the isolation of this 
element very difficult. Messrs. Knox, of Ireland, and 
Baudrimont, of France, have so far succeeded in effecting 
its separation as to leave no doubt of its being a yellowish 
brown gas, having the smell and bleaching properties of 
chlorine. It does not act on glass, (as its compound with 
hydrogen does,) but it unites directly with gold. Its specific 
gravity is 1-289. Its associations and characteristic prop^ 
erties all show most decidedly that it must be classed with 
the oxygen group, and it is, in common with its associates, a 
powerful negative electric. 

^ 280. The compounds of fluorine, which we shall men-* 
tion, nearly all belong to subsequent groups. It forms no 
known compound with oxygen. Mr. Leeson has recently 
succeeded in combining it with iodine and bromine. 
When a mixture of fluor-spar with peroJcyd of manganese 
and sulphuric acid: is heated, a reaction takes place, (^261,) 
by which fluorine in an impure form is disengaged. If 
the gas thus produced is passed through iodine suspended 
in waterj combination takes place, and a fluorid of iodine is 
formed, which crystallizes in yellow scales. A fluorid of 
bromine is formed by a similar process, w^hich has been 
used in the photographic art with success. It is not crys- 
tallizable. The precise composition of these bodies is not 
known. 

§ 279. What has prevented the study of fluorhie ? What is known of 
it? To what is it allied closely? Does it unite with oxygen? §280* 
What compounds of it are named in this section ? 



192 



SULPHUR. 



VI. SULPHUR. 



Equivalent, 1609. Symbol, S. Density in vapor, %Q'AS. 

§ 281. History. — Sulphur is one of those elements known 
from remotest antiquity. It occurs abundantly in many 
volcanic regions ; as in the island of Sicily, the vicinity of 
Naples, and many islands of the Pacific. It is also found 
in beds of gypsum, as a rock, near Cadiz in Spain, and at 
Cracow in Poland. Its compoands (sulphurets) wuth iron, 
copper, and other metals, are widely spread over the earth, 
and in combination as sulphuric acid it forms a large part of 
common gypsum or plaster of Paris. 

§ 282. Properties. — It is a straw-yellow and brittle solid at 
common temperatures, having a gravity of 1-98. In crystal- 
line form it is dimorphous, (^ 232.) Its usual form is the 
rhombic octahedron, (^ 221,) as in the figure. Na- 
tive sulphur has this form or its modification, and so 
has sulphur deposited in crystals from solution. 
But if it is fused (as in a crucible) and allowed to 
cool gradually, and the crust is broken before the 
whole of the interior mass is solidified, a part 
may be turned out, while the remainder has the 
form of long, slender, confused prisms, as in the an- 
nexed figure. This difference of form is the result of tem- 
Sulphur melts at 226°, and from that point to 
280° is a clear amber-colored fluid. At 
about 320° it begins to stiffen and grow 
reddish, and from that point to about 
480° it is so stiff that the vessel containing 
it may be turned over without spilling it. 
In this state it copies seals, medallions, 
&c., very perfectly, and is much used 
for this purpose. At 482° it becomes 
more fluid, and remains so until it reaches its boiling 
point at 601°. It is very volatile, and sublimes readily 
even below its boiling point, forming flowers of sulphur. 
This is the method used to purify it from the earthy matters 
found with it. It is also cast into long cylinders, and is 




perature. 




^281. Give the natural history of sulphur. § 282. What are its prin- 
cipal properties ? Describe its crystallization and fusion. Is it volatile ? 



SULPHUR. 193 

then called * roll sulphur.' When cold it has no odor, and 
the warmth of the hand causes it to crackle, from a distur- 
bance of its crystalline structure. By warmth and friction 
it acquires its well known brimstone smell. It is eminently 
a non-conductor of electricity, and is easily excited to give 
negative electrical sparks by friction. 

Sulphur is insoluble in water and tasteless. It is dis- 
solved by oil of turpentine and some other oils, and more 
readily in liquid sulphuret of carbon. Its vapor is soluble in 
vapor of alcohol, but fluid alcohol does not dissolve solid 
sulphur. A little hydrogen is always found in flowers of 
sulphur, mechanically entangled there. 

(^ 283. In its chemical relations it much resembles oxy- 
gen. It forms sulphurets with most of the elements that 
form oxyds, and these sulphurets often unite to form bodies 
analogous to salts, as the oxyds do. Berzelius with much 
reason argues that its binary combinations, from their anal- 
ogy to the oxyds, should be called sulphids. 

Its uses are well known. It is one of the essential in- 
gredients of gunpowder, and is the basis of all kinds of 
matches. Nearly all the sulphuric acid used in the arts is 
made from it. The gas arising from its combustion is em- 
ployed in bleaching straw and woolen goods ; and in medicine 
it has a specific power in certain obstinate cutaneous diseases. 

1 . Compounds with the members of the Oxygen Group, 
§ 284. With oxygen it unites in several proportions. It 
burns in common air with a pale blue flame, and gives the 
well known odor ©f a burning match, forming only sulphurous 
acid, which is its lowest compound with oxygen. The 
known compounds of sulphur and oxygen are 

Combination by wt. 

Srmlinl. 

Sulphurous acid, 
Sulphuric acid, 
Hyposulphurous acid, 
Hyposulphuric acid, 
Sulphureted hyposulphuric acid, 
Bisulphureted hyposulphuric acid, 

Has it odor when cold ? How does it act as an electric ? In what is it solu- 
ble ? § 283. What are its chemical relations ? Why is it associated in 
the oxygen group? Name its iise^- § 284. What compounds does it 
form with oxygen ? 

17 



Symbol. 


Sulphur. Oxygen. 


so„ 


16-09 


16 


SO3 


1609 


24 


s„o. 


32-18 


16 


s,o. 


32-18 


40 


S305 


48-27 


40 


S40, 


64-36 


40 



194 NON-METALLIC ELEMENTS. 

We need now mention particularly only the first two of 
these compounds. 

^ 285. (1.) Sulphurous acid, (SO2 ) — This is the sole 
product of the combustion of sulphur in common air or pure 
oxygen gas. But for experiment it is prepared by the action 
of sulphuric acid (SO 3) with heat on copper clippings or 
mercury, in a glass retort. One equivalent of oxygen is re- 
tained by the metal, and the other two with the sulphur are 
given off as sulphurous acid. Sulphurous acid is one of the 
gases which must be collected over mercury, or by displace- 
ment of air in dry vessels. Its high specific gravity renders 
it easy to do the latter. 

^ 286. Properties. — This is a colorless gas, having a 
density of 2-21 : 100 cubic inches of it weigh 68 69 
grains. It has a very pungent, suffocating odor, quite in- 
sufferable, and it at once extinguishes flame. A lighted 
candle lawered into a jar containing it is extinguished, and 
the edges of the ffame, as it expires, are tfnged with green. 
A solution^ of blue litmus or blue cabbage turned into a jar 
of the gas is at first reddened by the acid and then bleached. 
Water absorbs 37 times its volume of sulphurous acid, 
forming a strongly acid fluid. Its avidity for moisture is so 
great that it forms an acid fog with the water in the at- 
mosphere, and a bit of ice slipped under a jar of it on the 
mercurial cistern is instantly melted ; the water absorbs the 
gas and the mercury rises to fill the jar. Its bleaching 
power is only temporary. Articles bleached by it after a 
time regain their previous color. 

§ 287. Sulphurous acid is easily condensed by cold and 
pressure into a fluid having a specific gravity of 1*45, 
which becomes a crystalline, transparent, colorless solid at 
— 105°. The solid is heavier than the liquid, and sinks in 
it. 

By volume, sulphurous acid contains one volume of oxy- 
gen and i volume of sulphur vapor, (^ 190,) condensed into 
one volume. Sulphurous acid forms a series of salts [sul- 
phites) with bases, some of which we may notice hereafter. 

§285. How is sulphurous acid formed? How is it collected? §286. 
Give its properties. Does it support the conabustion of a caudle ? How 
does it affect vegetable colors? Is it dissolved by water? What of its 
avidity for moisture ? Does it bleach permaueutly ? § 287. Does it be- 
come liquid? At what temperature is it solid? Give its composition by 
volume. 



SULPHUR. 



195 



^ 288. (2.) Sulphuric acid, (SO3, HO.) — This acid is one 
of the most, important compounds known ; its affinities are 
very powerful, and no class of bodies is better understood by 
chemists than the sulphates. In the arts, great use is made 
of sulphuric acid, many millions of pounds of it being annu- 
ally consumed in manufacturing nitric and muriatic acids, 
the sulphate of copper, and alum, and in the process of dyeing. 

It is not formed by the direct union of its elements, since 
we have seen that only sulphurous acid can result from the 
combustion of sulphur in air. Sulphurous acid must be ox- 
ydized to form sulphuric acid. 

§ 289. This may be done by passing a mixture of sulphu- 
rous acid v^ith common air over spongy platinum, heated 
to redness in a tube, when there will issue from the open 
end of the tube a mixture of sulphuric acid in vapor, with 
nitrogen from the air. In the arts, however, this process can- 
not be used ; but sulphuric acid is made on a large scale by 
bringing together sulphurous acid, (SOo,) nitrous acid, (NO^, 
^ 302,) and water, (HO,) all inastate of vapor, in a large cham- 
ber or room, when sulphurous acid (SO2) passes to a higher 
state of oxydation (SO 3) at the expense of one half the oxygen 
of the nitrous acid, (NO^) which thus becomes reduced 
to the state of the * t 

deutoxyd of , ni- j/ j'^ 

trogen, (NO 3.) — ~^~--_™— 

The arrangement 
employed is repre- 
sented in the an- 
nexed figure. AA, 
is a chamber fifty 
feet or more long, 
lined on all sides 
with sheet lead. 
A very large leaden 
tube (B) opening 
into one end of the chamber, communicates with a furnace. 
Its lower end rests in a gutter (c c) of dilute acid, to prevent 




§288. What is said of the importance of sulphuric acid? What are 
its chief uses in the arts ? How is it formed ? § 289. How may sulphurous 
acid be oxydized? How is it done in the arts? Of what use are the 
nitric and nitrous acids, in this process ? Describe the arrangement of 
the leaden chamber. What vapors enter the chamber? 



196 NON-METALLIC ELEMENTS. 

the effects of too much heat, and the escape of the vapors. The 
sulphur is introduced by a door (c) to an iron pan, and a fire 
built beneath, (n,) The heat mehs the sulphur, which burns 
in a current of air passing over it, and the sulphurous acid 
thus formed enters the chamber in company w^ith air and 
the vapors of nitric acid set free from small iron pans standing 
over the sulphur, and containing the materials to evolve ni- 
tric acid, (sulphuric acid and saltpetre.) A small steam 
boiler (e) furnishes a jet of steam (x) as required, and a 
quantity of water covers the floor, which is inclined so as 
to be deepest at h. A chimney with a valve or damper (p) 
allows the escape of spent and useless gases. Things being 
thus arranged, the chamber receives a constant supply of sul- 
phurous acid, common air, nitric acid-vapor, and steam. These 
leact on each other, the nitric acid (NO^) gives up a part 
of its oxygen to the sulphurous acid, forming nitrous acid, 
(NO4,) and finally the deutoxyd of nitrogen, (NOo.) The 
last substance in contact with air gains another equivalent of 
oxygen, to form nitrous acid anew, which is again destined 
to be deoxydized by a fresh portion of sulphurous acid. In 
this way a small quantity of nitric acid can be made to ox- 
ydize an indefinite amount of sulphurous acid ; serving the 
purpose, as it were, of a carrier of oxygen, from the atmos- 
pheric air to the sulphurous acid. Meanwhile the water on the 
floor of the chamber grows rapidly acid, and when it has 
attained a specific gravity of about 1-5, it is drawn off and 
concentrated by boiling, first, in open pans of lead until it 
becomes strong enough to corrode the lead, and afterwards 
in stills of platinum until it has a density of about 1*8, in 
which state it is sold in carboys, or large bottles packed in 
boxes. 

§ 290. The process of forming sulphuric acid is easily 
illustrated in the class-room, by an arrangement of apparatus 
like that shown in the adjoining figure. Two flasks {a h) 
are so connected by bent tubes with a large bottle, that 
from one {a) sulphurous acid, and from the other {h) nitric 
oxyd gases (§ 302) are made to pass into the middle bottle, the 



What use is made of steam ? What receives and condenses the va- 
pors ? Explain the successive changes which take place in the chamber. 
How can a small quantit)^ of nitric acid answer the purpose ? How is 
the acid water from the chamber concentrated ? § 290. How can we 
illustrate this process in the class-room ? 



SULPHUR, 



197 




inner surface of which is slightly moistened. By blowing 
in occasionally at c, the spent gases are ejected at cZ, and 
fresh air introduced. Under these circumstances the in- 
terior of the central ves- 
sel is soon covered with 
a white crystalline solid,, 
which appears to be a 
compound of sulphurous 
acid and nitrous acid, 
(80^,^0^.) This sub- 
stance is decomposed by 
a larger quantity of water 
into sulphuric acid and 
hyponitrous acid, and as 
it is known to be formed 
in the leaden chambers in large quantities, it is supposed to 
have an important influence in the production of sulphuric 
acid.* 

^ 291. Sulphuric acid unites with water in four pro- 
portions ; namely, 

Nordhausen acid, 
Oil of vitriol. 
Acid of sp. gr, 1*78, 
Acid of sp. gr., 1*63, 

§ 292. The most concentrated sulphuric acid, however, is 
made by distilling dry sulphate of iron in earthenware re- 
torts, at a red heat, when the acid of the salt with half an 
equivalent of water comes over in vapor and is condensed 
in earthen tubes. It is a dark-brown, oily fluid, of the spe- 
cific gravity of 1'9, or nearly twice as heavy as water, and 
with such an avidity for water as to hiss like hot iron 
when dropped into it. This sort of acid is made at Nord- 
hausen, in Saxony, and is commonly called the Nordhausen 
sulphuric acid. It has the composition of 2SO3, HO=:89*19. 

Explain the arrangement and reaction. What is the composition of 
the white cr3^stalline compound? How does water affect it? §291. 
"What compound does sulphuric acid form with water? §292. How is 
the strongest sulphuric acid made ? What is its character? its strength ? 
its formula ? What is it called ? 



2(803) HO 
SO3, HO 
SO3, HO+HO 
SO3, H0+2H0 



* We can express this decomposition in symbols thus, (SO34-NO4,) 
give (SO3-I-NO3) 3NO3 gives NO5 andSNOa- 

17* 



198 NON-METALLIC ELEMENTS. 

When it is put in a retort and moderately heated, a silvery . 
crystalline product is obtained from it, which is dry, or anhy- 
drous sulphuric acid, (SO 3.) Common sulphuric acid, when 
as strong as possible, has still one equivalent of water, as 
above. It also unites with two equivalents, (S03,H0+H0,) 
with a specific gravity of ] -780. When acid of this strength 
is exposed to a temperature of 32° it freezes in large crystals. 
Great heat is generated from the mixture of strong sulphuric 
acid and water, and a diminution of bulk attends the mixture. 
When exposed to a temperature of 15° sulphuric acid freezes ; 
and at 620° it boils, giving off a dense white vapor. It is in- 
tensely acid to the taste, and deadly, if by any accident it is 
swallowed, corroding and burning the organs with intense 
heat. It blackens nearly all organic matters, charring or 
burning them like fire. Its strong disposition for water en- 
ables us to employ it in desiccation, and in the absorption 
of aqueous vapor, (§ 122.) 

^293. The silky anhydrous coinpound (SO 3) obtained from 
the distillation of Nordhausen acid, (2SO3 + HO,) does 
not possess acid properties when dry, but water at once 
changes it to common sulphuric acid. It has therefore 
hQQXi inferred that sulphuric acid cannot exist without 
water, or that water is essential to the acid property. In 
this case it is supposed that the oxygen of the water joins 
that already with the sulphur, (forming SO^,) while the 
new compound thus produced unites with hydrogen, forming 
SO^H. There is reason to believe that this view of the 
case may be true, especially from what is known of the com- 
position of salts, in which it seems probable that the metallic 
base of the salt replaces the hydrogen. This is called the 
" salt radical theory J^ 

2. Compounds of Sulphur, with other members of the 
Oxygen Group, 

§ 294. Chlorid of sulphur is prepared by passing dry 
chlorine over melted sulphur. It is a volatile deeply colored 

Give the composition of the common sulphuric acid. At what strength 
and temperature does it freeze ? When mingled with water, what hap- 
pens? Give other properties of sulphuric acid ? § 293. Is the silky com- 
pound acid? To what does the common acid owe its acid properties? 
What view is given of the possible arrangement of its atoms ? What is 
it called ? § 294. What compounds does sulphur form with other mem- 
bers of the oxygen group ? 



SELENIUM. 199 



liquid of a disagreeable odor, boils at 280^, and has a den- 
sity of 1-687. It consists of two equivalents of sulphur and 
one of chlorine, (SgCl.) It is decomposed by water. 

There are also bromids and iodids of sulphur, which 
however possess very little interest. 



VII. SELENIUM. 

Equivalent, 39'57. Symbol, Se. Density/, 4*3. 

§ 295. History and Properties. — This element was dis- 
covered by Berzelius in 1818, and named by him from selene, 
the moon. It is associated in nature with sulphur in some 
kinds of iron pyrites, and also at the Lipari Islands, com- 
bined with sulphur and accompanied by other volcanic pro- 
ducts. 

It closely resembles sulphur in most of its properties, as 
well as in its natural associations. At common tempera- 
tures it is a brittle solid, opake, and having a metallic lustre 
like lead, but in powder it is of a deep red color. Its spe- 
cific gravity is between 4*3 and 4*32. It softens at 212°, 
and may then be drawn out into red colored threads ; at a 
little higher temperature it melts completely and boils at 
650°, giving a deep yellow vapor without odor. It is insol- 
uble. When heated in the air it combines with oxygen and 
gives out a disagreeable and strong odor, like putrid horse- 
radish. Before the blowpipe, on charcoal, it burns with a 
pale blue flame, and ^V of a grain, so heated, will fill a large 
apartment with its odor. It is a non-conductor of heat and 
of electricity. 

§ 296. The compounds of selenium with oxygen are three, 
two of which are acids analogous to sulphurous and sulphu- 
ric acids. Their composition is, 

Composition by weight. 

Oxyd of Selenium, 
Selenious acid, 
Selenic acid, 

§295. When, where, and by whom was selemum discovered? Give 
its properties. What physical property most distinguishes it? §296. 
What are its compounds with oxygen? 



Symbol. 


Selenium. 


Oxygen 


SeO 


39-57 


8 


SeO, 


39-57 


16 


SeO, 


39-57 


24 



200 



NON-METALLIC ELEMENTS. 



^ 297. Oxyd of selenium is formed when selenium is heat- 
ed in the air. It is a colorless gas, and possesses the strong 
odor before mentioned. Selenious acid is a white and very- 
soluble body, procured by the action of nitric acid on sele- 
nium. It is distinctly acid, and can be sublimed without 
change of properties. Selenic acid is formed by oxydizing 
silenium with nitrate of potash. It strongly resembles 
sulphuric acid in its acid properties and compounds. Both 
selenious and selenic acids form salts with the alkalies and 
bases, every way similar to the sulphites and sulphates. 

Selenic acid, it is said, may also be formed by the action 
of nitric acid on selenium. With sulphur, selenium forms a 
sulphuret which is found native among volcanic products. 

CLASS II. THE NITROGEN GROUP. 



I. NITROGEN, OR AZOTE. "" 

Equivalent^ 14'06. Symbol, N. Density, -972. 

^ 298. Preparation and History.— This gas forms four- 
fifths of the air we breathe, and is found as an essential con- 
stituent of most organic substances. It enters into a great 
variety of combinations. 

It is most easily procured for purposes of experiment from 
the atmosphere, by withdrawing 
the oxygen of the air by phospho- 
rus. This is easily done by 
burning some phosphorus in a 
floating capsule, in an air-jar 
over the pneumatic cistern. The 
strong affinity of phosphorus 
for oxygen enables it to withdraw 
every trace of this element, leav- 
ing behind nitrogen nearly pure, 
containing about ^ of phosphorus 




§297. Characterize these compounds. (1.) The oxyd ; (2.) Selenious 
acid ; (3.) Selenic acid. § 298. Give the symbol and equivalent of nitro- 
gen. How is it prepared ? 



* So called from a, privative, and zoe, life, from its deadly effects. 
Nitrogea is from nitrurtif nitre, and gennao, I form. 



NITROGEN. 201 

and the vapors of phosphorus, with the snow-white phospho- 
ric acid which the water soon absorbs. The first combus- 
tion of the phosphorus expels a portion of the air by expan- 
sion ; but as the combustion proceeds, the water rises in the 
jar, showing a considerable absorption. If this combustion is 
performed over mercury, the snowy phosphoric acid is beau- 
tifully seen, and remains dry, (§ 322.) Other processes 
might be used, such as passing air over cuttings of copper 
in a tube heated to redness, and by the action of nitric acid 
on lean animal muscle ; but the method first named will best 
suit our purposes. 

^ 299. Properties of Nitrogen. — Nitrogen is best descri- 
bed by saying that its properties seem entirely negative! It 
is a fixed gas which no degree of cold and pressure has 
ever liquefied. It cannot support combustion, nor life ; yet 
it is not poisonous, and kills merely by exclusion of air. It 
has neither taste nor smell. It is a little lighter than air, 
having a density of -972. It does not combine directly 
with any element, although by indirect methods it enters 
into powerful combinations with several. In the air, it 
seems to act the part of a diluent, and is not, properly speak- 
ing, in chemical combination with the oxygen there present ; 
the atmosphere is regarded rather as a mixture of the tv/o 
gases, diffused through each other, (§ 132.) 



1 . The Chemical History of the Atmosphere. 

^ 300. We have already (^ 24) given a sufficient account 
of the mechanical or physical properties of the atmosphere 
and the laws of gases, and need not repeat them here. The 
number and proportions of the constituents of the atmosphere 
are constant, although their union is only mechanical. Re- 
peated analyses have shown that atmospheric air is always 
formed of nitrogen, oxygen, watery vapor, a little carbonic acid, 
traces, perhaps, of carbureted hydrogen, and a small quantity 
of ammonia. The air on Mount Blanc, or that taken in a 



§ 299. What are its properties? Does it support life and combustion ? 
Is it poisonous? Does it directly combine with other elements? How 
does it act in common air ? § 300. Describe the chemical composition and 
properties of the air. Do the proportions vary ? Which constituents may 
vary? 



202 



NON-METALLIC ELEMENTS. 



balloon by Gay Liissac, from 21,735 feet above the earth, has 
the same chemical composition as that on the surface, or at 
the bottom of the deepest mines. The carbonic acid being 
liable to changes from local causes, is found to vary slightly. 
To the constituents already named, we may add the aroma 
of flowers and other volatile odors, which do not, however, 
afl^ect the purity of the air, and those unknown mysterious 
agencies which affect health, and are called miasma. We 
may state the composition of the atmosphere in 100 parts, 
to be — 

By Weight. Bv treasure. 

Nitrogen, 77 parts. 79 19 

.Oxygen, 23 20-81 



100 



iOOOO 



To this we must add from 3 to 5 measures of carbonic 
acid in 10,000 of air; a variable quantity of aqueous vapor, 
and a trace of ammonia. Nitric acid has also been sometimes 
found in small quantity in rain water, formed in the air by the 
electrical discharges of thunder-clouds, and washed out by 
the rains. 100 cubic inches of dry air weigh 31-011 grains. 
§301. Analysis of Air. — The oxygen of the air is ab- 
stracted by all substances having an affinity 
for it with the same ease as if nitrogen 
were not present. In fact, the experiments 
figured in § 298, is one mode of analyzing 
air. The term eudiometry has been applied 
to processes for determining the purity of the 
air, from words signifying ' a good condition of 
the air.' One of the simplest means of anal}^- 
zing the atmosphere, consists in removing the 
oxygen by the slow combustion of phospho- 
rus. For this purpose the arrangement is 
made, as in the annexed figure, by sustaining 
a stick of phosphorus on a wire in a confined 
portion of air, contained in a graduated glass 




Give its constitution by weiglit and measure. How much carbonic acid 
is there in it? What do 100 cubic inches weigh? §301. How is the 
air analyzed ? What is eudiometry ? Give a simple mode of illustrating 
the analysis of air. 



NITROGEN. 



203 



tube, whose open end is beneath water. Gradual absorption 
takes place, and in about twenty-foiirhoiirs the water 
has ceased rising in the tube, by which we know 
that the phosphorus has removed all the oxygen. 
The water absorbs the resulting phosphorus acid, 
and we n}ay read off, by the graduation on the 
tube, the amount of gas removed. A narrow-necked 
bolt-head shows this result in a more striking man- 
ner in the class-room, the large volume of air in the 
ball causing a very appreciable rise of water in 
the stem during the course of a lecture. When 
speaking of hydrogen, we will mention another 
method of eudiometry. The agency of the air in 
combustion and respiration will also be explained 
under the appropriate heads. From this mechanical mix- 
ture of oxygen and nitrogen, we pass to the 




2, Compounds of Oxygen and Nitrogen. 

^ 302. Nitrogen smites with Oxygen, forming five distinct 
compounds, three of which are acids. Their names and 
constitution are thus expressed : 



Protoxyd of nitrogen, (nitrous oxyd,) 
Deutoxyd of nitrogen, (nitric oxyd,) 
Hyponitrous acid, 
Nitrous acid, 
Nitric acid, 



This remarkable group of compounds is one of the most 
instructive examples of the law of multiple proportions 
(§ 183) in the whole range of .chemical affinities, and our 
attention is arrested by the startling fact, that the same ele-=- 
ments which form our salubrious air, should, by mere change 
of proportions, unite to form the corrosive and deadly acids 
of nitrogen. 

§ 303. Protoxyd of Nitrogen, (NO,) Nitrous Oxyd, or 





Combination by wt. 


Symbol. 


Nitrogen. Oxygen, 


HO 


14-06 8 


N0„ 


1406 16 


NO3 


1406 24 


NO, 


14-06 32 


NO. 


14-06 40 



§ 302. Name the compounds of oxygen with nitrogen. Give their 
composition on the black-board. 




204 NON-METALLIC ELEMENTS. 

Laughing Gas. — This gaseous compound of nitrogen is best 
prepared by heating nitfate of ammonia 
(NHgjNOJ in a glass flask by the 
aid of a spirit-lamp. The arrangement 
is here shown ; the gas is given ofT at 
about 400° to 500°, and is delivered 
by the bent tube to an air-jar on the 
pneumatic trough. The nitrate of 
ammonia, which is a crystalline white 
salt formed by neutralizing dilute 
nitric acid by carbonate of ammonia, 
is so constituted as to be resolved by 
heat alone, into nitrous oxyd and 
water; thus, NHg NO5 become by 
heat 3HO + 2NO. The hydrogen in 
the ammonia takes so much oxygen 
^rom the nitric acid — three equivalents — as is required to form 
three equivalents of water, and the nitrogen, both of the acid 
and ammonia, unites with the remaining oxygen to form the 
gas in question. Consequently in round numbers the equiv- 
alents of these elements show us that 71 grains of nitrate of 
ammonia will yield 44 grains of nitrous acid and 27 grains of 
water. Care must be taken not to heat this salt too highly, 
as it then yields nitric oxyd and nitrous acid fumes. If a 
white cloud of the undecomposed salt is seen to rise, the 
heat must be abated. 

§ 304. Properties. — Nitrous oxyd is a colorless gas, with 
a faint, agreeable odor, and a sweetish taste. With a pres- 
sure of fifty atmospheres at 45° F. it becomes a clear liquid, 
and at about 150° below zero freezes into a beautiful, clear, 
crystalline solid. By the evaporation of this solid, a de- 
gree of cold may be produced far below that of the carbonic 
acid bath (^ 137) in vacuo, (or lower than 174° F.) It evap- 
orates slowly, and does not freeze, as does carbonic acid, 
by its own evaporation. The specific gravity of nitrous 
oxyd is 1'525 ; 100 cubic inches of it weigh 47-29 grains. 
Cold water dissolves or absorbs about its own volume of 
this gas. It cannot, therefore, be long kept over water, but 

§303. How is protoxyd of nitrogen prepared? What caution is 
needed? §304. What are the properties of this gas ? Has it been so- 
lidified, and at what temperature? How does the solid gas behave? Is 
this an absorbable gas ? 



NITROGEN. 



205 



may be well enough collected in vessels filled with warm 
water over the water-trough. It supports the combustion 
of a candle, and re-lights its red wick with almost the same 
promptness and energy as pure oxygen. With an equal 
bulk of hydrogen, it forms a mixture which explodes with 
violence by the electric spark or a match, the residue being 
pure nitrogen, the oxygen forming water with the hydrogen. 

§ 305. Its most remarkable property , and that from which it 
gets the name of ' laughing gas,'' is its intoxicating power on 
the system when breathed. For this purpose it is breathed 
when pure or diluted with air, through a wide tube, con- 
nected with a siik or elastic gum bag or with a gas-holder, and 
may be inhaled and exhaled several times, until giddiness 
comes on, and a feeling of joyous or boisterous exhilaration. 
This is shown by a disposition to laughter, a flow of vivid 
ideas and poetic imagery, and often by a strong disposition 
to muscular exertion. These sensations are usually quite 
transient, and pass away without any resulting languor or 
depression. In a few cases dangerous consequences have 
followed its use, and it should be employed with great cau- 
tion. In at least one case,* at Yale College, it produced a 
permanent restoration of health and joyous exhilaration of 
spirits which continued for months. Its effects, however, 
in different individuals are various. 

§ 306. Deutoxyd or Binoxyd of Nitrogen, Nitric Oxyd. — 
This gas is easily prepared by adding strong nitric acid 
to clippings of sheet copper, contained 
in a bottle arranged with two tubes like 
the annexed figure ; a little water is 
first put with the copper cuttings, and 
the nitric acid poured in at the tall fun- 
nel tube until brisk effervescence comes 
on. In this case the copper is oxy- 
dized by a part of the"[oxygen of the acid, 
and the oxyd thus formed is dissolved 
by another portion of acid. The nitro- 
gen in union with two equivalents of 
oxygen is given off as nitric oxyd, 
which, not being much absorbed by 

§ 305. What is its most remarkable property ? How does it affect the sys- 
tem ? Are its effects uniform ? § 306. How is binoxyd of nitrogen formed ? 

* In another case consumptive symptoms resulted, which continued for 
years, although not eventually fatal. 

18 




206 NON-METALLIC ELEMENTS. 

water, may be collected over the water-trough. Many other 
metals have the same action with nitric acid. 

§ 307. Properties. — Nitric oxyd is a transparent, colorless 
gas, tasteless and inodorous, but excites a violent spasm in 
the throat when an attempt is made to breathe it. It has 
never been condensed into a liquid. Its specific gravity is 
1-039, and 100 cubic inches weigh 32*22 grains. It contains 
equal measures of oxygen and nitrogen uncondensed. 

A lighted taper is instantly extinguished when immersed 
in it, but phosphorus previously inflamed will burn in it with 
great splendor.* When this gas comes in contact with the 
air, deep red fumes are formed, by its union with the oxygen 
of the air to form nitrous acid. If to a tall jar, nearly filled 
with nitric acid, standing over the well of the cistern, pure 
oxygen gas be turned up, deep blood-red fumes instantly 
fill the vessel, much heat is generated, and a rapid absorp- 
tion results from the solution of the red nitrous acid vapors 
in the water of the cistern. If both gases are pure and in 
the right proportions, the absorption will be complete, and no 
gas be left in the vessel. If purple cabbage-water, made 
green by an alkali, is used to fill the air-jar, the acid formed at 
once turns the vegetable infusion to a lively red. 

^ 308. Hyponitrous Acid, (NO 3.) — This is a thin mobile 
liquid, formed from the mixture of four measures of deut- 
oxyd of nitrogen with one measure of oxygen, both perfectly 
dry, and exposed after mixture to a temperature below zero 
of Fahrenheit. It has an orange red vapor, and at common 
temperatures is green, but at zero is colorless. Water decom- 
poses it, forming nitric acid and deutoxyd of nitrogen. Its 
most interesting compound is that formed with sulphurous 
acid in the manufacture of sulphuric acid, (§ 289,) as al- 
ready described. 

§ 309. Nitrous Acid, CNO^.) — We have already anticipated 
the mode of forming this compound and its properties in de- 
scribing the deutoxyd of nitrogen. Whenever the latter 

§ 307. What are its properties? Is it respirable? Condensable? 
Give its specific gravity and its composition by volume. Does it support 
combustion? What is its action with oxygen ? What fine experiment 
is named? §308. What is hyponitrous acid? What compound of it 
have we already described? 

* It is extinguished if not previously burning with energy. 



NITROGEN. 



207 



body is brought into contact with the air, red nitrous acid fumes 
are formed. By decomposing the nitrate of lead in an earthen 
retort nitrous acid may be obtained in a very cold receiver 
alono- with pure oxygen gas. In this state it is a nearly 
colorless fluid, which becomes of a yellow and finally red color 
as the temperature rises. It boils at 82°, and is decomposed 
by water ; nitric acid and deutoxyd of nitrogen being 
formed. 

This body is not a very well characterized acid, although 
universally considered as one. The red color of the strong, 
fuming nitric acid of commerce, is due to the presence of 
nitrous acid dissolved in the fluid. 

^ 310. Nitric Acid, Aqua Fortis of the arts, (NO5.) — This 
powerful and important acid is better known than any other of 
the compounds of nitrogen. It is best obtained by decompos- 
ing either the nitrate of soda or of potash, (saltpetre,) by strong 
sulphuric acid. The ar- R 
rangement of apparatus 
required is seen in the 
adjoining cut. The re- 
tort (R) contains the 
nitre in small crystals, 
and should be supported 
in a sand-bath ; or, if the 
salt does not exceed a 
pound or two, a naked fire 
answers very well. To it 
is added about twice its 
weight of strong oil of vit- 
riol. The sulphuric acid 
takes the place of the 
nitric, forming bisulphate 
of soda or potash, and the strong nitric acid distills over to 
the receiver, which is kept cool by water or ice, and no luting 
of any kind must be employed about its neck. The belly of 
the retort becomes very hot, and the whole operation is a crit- 
ical one. The dense red vapors of nitrous acid which ap- 




§ 309. What is said of nitrons acid ? How can it be obtained ? Can 
it be mixed with water? § 310. How is nitric acid formed? Describe 
the arrangement of apparatus and the proportions of the materials. 
What changes are noticed as the process goes on ? When is the process 
arrested ? 



# 



208 NON-METALLIC ELEMENTS. 

pear in the early stage of the process disappear entirely 
after a time, and are again renewed toward its close. 
When the deep blood-red vapors prevail, and but little acid 
condenses in the neck of the retort, the heat is remitted and 
the receiver disconnected ; the bisulphate of potash is then 
in a state of quiet fusion and intensely hot, (about 600° F.) 
When nearly cold it may be gradually dissolved by hot 
water, but the retort is generally sacrificed in the experiment 
The strongest nitric acid is produced only when equal 
weights of sulphuric acid and nitre are used. 

§ 311. Properties. — Nitric acid thus obtained is a highly 
colored, red, fuming, and very corrosive acid, of great 
energy. The color is due to nitrous and hyponitrous acid, 
the pure nitric acid being colorless, with a specific gravity 
of 1-5, and boiling at 18?°. It stains the skin yellow, and 
acts violently on most organic matters and metals. Poured 
on powdered recently ignited charcoal, deflagration speedily 
ensues, and oil of turpentine a little warm is at once in- 
flamed by it. 

§ 312. One equivalent of water is essential to the character 
of nitric acid, (NO^, HO,) the simple NO. being an unknown 
substance. The strongest nitric acid has nine parts of 
water to 54 of real acid. Like sulphurous acid, it has sev- 
eral definite combinations with water, w^hich freeze and 
boil at very different comparative temperatures. Strong 
aqua fortis freezes at about 50° below zero, but when diluted 
with one-half water it freezes at — 1^°. The green hydrated 
nitrous acid freezes into a bluish white solid. 

§ 313. It oxydizes other substances very powerfully, from 
the great amount of oxygen it contains. It is the usual 
solvent of most of the metals, when we would carry them to 
the condition of peroxyds. In all such cases, the binoxyd 
of nitrogen is formed, (NO^,) which at once produces red 
fumes in the air. It forms a large class of salts, (nitrates,) 
all of which are soluble in water. This makes it difficult 

§ 311. What are its properties ? What gives its ordinary color ? How 
does it affect the skin, the metals and charcoal? 312. Is the anhydrous 
nitric acid known? What is the composition of the strongest nitric 
acid? Is it ever frozen, and at what temperature? 313. How does it 
affect other bodies ? 

* By using a larger proportion of sulphuric acid and by waiting until 
the fused salt has nearly cooled, the retort may behaved. 



PHOSPHORUS. 209 

to detect the presence of this acid. It however decolorizes 
a solution of indigo in sulphuric acid, which is the common 
test for the presence of nitric acid ; and with a drop or two 
of hydrochloric acid it at once dissolves gold leaf. 



II. PHOSPHORUS. 

Equivalent, 31*38. Symbol^ P. Density, I '77. 

^314. History. — Phosphorus is an element nowhere 
seen free in nature, but it exists largely in the animal kingdom, 
combined with lime, forming bones, and it is found also in 
other parts of the body. In the mineral kingdom it exists 
in several well known forms, particularly in the mineral 
called apatite, or phosphate of lime. It is introduced into 
the animal system by the plants used as food, whose ashes 
contain a notable quantity of phosphate of lime. It was 
discovered in 1669 by Brandt, an alchemist of Hamburg, 
while engaged in seeking for the " philosopher's stone," in 
human urine. Its name implies its most remarkable prop- 
erty, (phos, light, and p hero, I carry.) 

§ 315. Preparation. — Phosphorus is now procured in im- 
mense quantities from burnt bones, for the manufacture of 
friction match-es. The bones are calcined until they are 
quite white ; they are then ground to a fine powder, and 
fifteen parts of this are treated with thirty parts of water 
and ten of sulphuric acid : this mixture is allowed to stand 
a day or two, and is then filtered, to free it from the insoluble 
sulphate of lime, formed by the action of the oil of vitriol on 
the bones The clear liquid (which is a soluble salt of lime 
and phosphoric acid) is then evaporated to a syrup, and a 
quantity of powdered charcoal added. The whole is then 
completely dried in an iron vessel and gently ignited. After 
this, it is introduced into a stoneware or iron retort, to which 
a wide tube of copper is fitted, communicating with a bottle 
in which is a little water, that just covers the open end 
of the tube ; a small tube carries the useless gases given 
out to a chimney or vent. The retort being very gradually 



§ 314. What is phosphorus ? When and by whom discovered ? What 
existence has it in nature? §315. How is it prepared? Describe the 
process of procuring it. 

18* 



210 



NON-METALLIC ELEMENTS. 




heated, the charcoal decomposes the phosphoric acid, car- 
bonic acid and carbonic oxyd gases 
are evolved, and free phosphorus 
flows down the tube into the bottle, 
where it is condensed. The oper- 
ation is a critical one, and often fails 
from the breaking of the retort. — 
Splendid flashes of light are con- 
stantly given out during the opera- 
tion, from the escape of phosphuret- 
ed hydrogen. The crude phospho- 
rus thus obtained is purified by melt- 
ing under water, and is then cast into 
glass tubes, where it is allowed to 
cool, forming the sticks in which it is sold. 

^316. Pure phosphorus is a yellowish semi-transparent 
solid, which cuts like wax, is brittle at 32°, and then shows 
a crystalline fracture. It has a density of 1*77. It is in- 
soluble in water, but dissolves in several oils, in ether, al- 
cohol, and in sulphuret of carbon : from the last it crystal- 
lizes in regular dodecahedrons, (§ 219.) It melts at 108° 
into a colorless liquid, and at 550° it boils, forming a color- 
less vapor of a density of 4-327. 

§ 317. Phosphorus is exceedingly inflammable, being easily 
set on fire by the heat of the hand, and great caution is required 
in managing it. It must be kept under water, to which al- 
cohol enough may be added to prevent its freezing in winter. 
If exposed to the air, it wastes slowly away, in an acid fog, 
forming phosphorous acid, and in the dark it is seen to be lu- 
minous. The vapor which then comes from it, has a strong 
garlic odor, which does not belong either to the pure phos- 
phorus or any acid compounds. A little defiant gas, or 
the vapor of ether, or any essential oil, will entirely arrest 
the slow oxydation of phosphorus in air. The presence of 
nitrogen or hydrogen seems to be essential to this operation, 
as even in pure oxygen, phosphorus does not form phospho- 
rous acid at common temperatures. It burns in pure oxygen 
gas with a splendor almost too great to behold. For this 



§316. What is its usual condition? In what is it soluble? How is 
its density when solid and in vapor ? § 317. What of its inflammability ? 
How is it kept? How does air affect it ? What substances arrest its slow 
combustion ? How does it burn in oxygen ? 



PHOSPHORUS. 211 

purpose it is suspended in a metallic spoon, in a dry globe, 
filled with oxygen by displacement of air, as already de- 
scribed, 

1. Compounds of Phosphorus loith Oxygen, 

§ 318. The compounds of phosphorus with oxygen are four 
in number, and may be understood from the following list. 

Composition by Weight. 



Oxyd of phosphorus, 
Hypophosphorous acid, 
Phosphorous acid. 
Phosphoric acid. 


Symbol. 

P.o 

PO 

P03 


Phosphorus. 

62-76 

-* 31-38 

31-38 

31-38 


Oxygen. 

8 

8 
24 
40 



^319. Oxyd of phosphorus is formed when a stream of 
oxygen gas is allowed to flow from a tube upon phosphorus 
iinder warm water. The phosphorus burns under water 
and forms a brick-red powder, which is the oxyd in ques- 
tion, with much unburnt phosphorus. This oxyd is also 
formed when phosphorus is kept for a long time under 
water ; the sticks then become coated with the red oxyd. 
By heat, this oxyd is decomposed into phophorus and phos- 
phoric acid. 

^ 320. Hypophosphorous acid is very little known, and we 
need not describe its mode of formation. Its salts are all 
soluble in water, and it is a powerful deoxydizing agent. 

^ 321. Phosphorous Acid, — When some sticks of phos- 
phorus are placed in a funnel, and its mouth covered, a 
minute stream of white vapor is seen to descend from the 
lower end of the tube, which may be collected in a tall 
foot-glass. These vapors are mainly phosphorous acid, 
from the slow combustion of the phosphorus by the oxygen 
of the air. It is also formed when phosphorus is burnt in 
a very limited supply of oxygen gas. In both cases it soon 
takes another dose of oxygen from the air, and so becomes 
a mixture of phosphorous and phosphoric acids. 

When first made phosphorous acid is a dry white powder, 
having a very strong affinity for water, which it absorbs with 
oxygen from the air, and gradually becomes phosphoric acid. 

§ 3 J 8. Name its compounds with oxygen, and give the formulas. §319. 
Describe the oxyd, its formation and properties. How does heat affect 
it ? § 320. What of hypophosphorous acid ? § 321. How is phosphorous 
acid formed ? What are its properties ? 



212 NON-METALLIC ELEMENTS. 

Its solution is sour, and it forms well determined salts, (phos' 
phites.) 

§ 322. Phosphoric acid is formed when phosphorus is 
burned in a copious supply of dry air, as in the experiment 
for obtaining nitrogen, (^ 298,) or that of phosphorus in 
dry oxygen, (§ 317.) When wanted in large quantity, it is 
prepared from the ashes of bones treated with sulphuric 
acid, as already described. This solution is first freed 
from lime and magnesia, by methods we need not now 
mention, and is then evaporated to dryness and ignited, when 
the sulphuric acid is driven off and phosphoric acid 
remains behind melted, and solidifies on cooling into a col- 
orless glass, which is then called glacial phosphoric acid. 
Phosphoric acid is also formed by the action of very strong 
nitric acid on phosphorus ; but the operation is a dangerous 
one, and should be attempted only on very small quantities 
of phosphorus, and with extreme caution. 

§ 323. Phosphoric acid is a powerful acid, having an in- 
tensely sour taste, and all the attributes belonging to an acid. 
It has, when dry, a very strong affinity for water, and 
unites with it almost explosively, forming, according to cir- 
cumstances, three distinct compounds, or phosphates of watery 
whose constitution is as follows ; 

Monobasic phosphate of water, or raetaphosphoric acid, HO-I-PO5. 
Bibasic phosphate of water, or pyrophosphoric acid, 2HO-(-P05 . 

Tribasic phosphate of water, or common phosphoric acid, SHO-j-POg. 

Each of these three phosphates of water is the source of 
a distinct series of salts with bases. The class of salts most 
generally known is that formed from the last phosphate of 
water, or the tribasic phosphates. The reader can consult 
Dr. Graham's Elements of Chemistry for a fuller account 
of this subject, which our limits prevent our giving in more 
detail. Science is much indebted to Prof. Graham for his 
able researches on the phosphates and arseniates. 

2. Compounds of Phosphorus, with other Members of the 
Oxygen Group, 

§ 324. (1.) Chlorids of Phosphorus. — Of these there are 

§322. How is phosphoric acid formed? How from bones? §323. 
Describe its properties. How does water affect it ? Give its compounds 
with water. Which is common phosphoric acid ? 



PHOSPHORUS. 213 

two, the perchlorid, (P2CI5,) and sesquichlorid, (P.Clg.) 
The first is formed when phosphorus is introduced into a 
jar of dry chlorine, where it inflames and lines the sides of 
the vessel with a white matter, which is the perchlorid of 
phosphorus. This compound is very unstable, and when 
put in water both it and the water suffer decomposition, and 
hydrochloric and phosphoric acid result. 

§325. (2.) Bromids of Phosphorus. — Two of these com- 
pounds' are also known, and are easily formed by mingling 
small quantities of the elements in a flask flUed with dry 
carbonic acid gas ; they immediately react on each other, 
evolving heat and light, and form the protohromid of phospho- 
rus^ (PBr,) which is a brown fluid, easily decomposed by 
water; and the perbromid of phosphorus, (P^^^sO which is 
a volatile yellowish white solid, that sublimes on the sides 
of the flask and is easily fused by gentle heat into a red 
fluid. It is decomposed by water into phosphoric and hy- 
drobromic acids. 

§ 326. (3.) lodids of Phosphorus. — These elements com- 
bine in three proportions, forming protiodid of phosphorus, 
(PI,) sesquiodid of phosphorus, (P^Ig,) and the periodid 
of phosphorus, {F^l^-) The union of these elements is ac- 
complished with energy by simple contact of both in a dry 
state. Their compounds are not important. 

§ 327. (4.) Sulphuret of Phosphorus. — Sulphur unites 
with phosphorus with prodigious violence, frequently with 
a dangerous explosion, and more than 30 or 40 grains of the 
latter cannot be safely put with the sulphur. Seleniuret 
of phosphorus is formed in the same manner as the last, and 
is similar to it in all its properties. 

3. Compound of Phosphorus with Nitrogen. 

§ 328. Phosphuret of Nitrogen, (NP^.) — This compound 
is formed by the action of dry ammonia on the chlorids of 
phosphorus ; or more conveniently, by acting on the chlora- 
mid of mercury, (white precipitate,) by bits of phosphorus 



§ 324. Name the chlorids of phosphorus. § 325. How many bromids 
of phosphorus are there? How are they formed ? § 326. How many 
iodids of phosphorus, and how formed? § 327. What is said of the miioii 
of sulphur and phosphorus ? What of its seleniuret? § 328. What com- 
pomid do phosphorus and nitrogen form ? Give its formula and prepara- 
tion. What are its properties? 



214 



NON-METALLIC ELEMENTS. 



in a flask of hard glass, filled with carbonic acid. The ni- 
trogen of the white precipitate is thus taken up by the phos- 
phorus, and the mercury and muriate of ammonia liberated 
are expelled by a dull-red heat. There remains behind a 
snow-white insoluble powder, which resists even a red heat, 
and does not decompose at that temperature even in chlorine 
gas or vapor of sulphur. Fused potash, and hydrogen at red- 
ness, decompose it, with the escape of ammoniacal gases. 
It contains two equivalents of phosphorus and one of nitro- 
gen. 

CLASS III. THE CARBON GROUP. 

I. CARBON. 

Equivalent, 6. Symbol, C. Specific gravity in vapor, 0-421. 
Solid in the diamond, 3-52. 

§ 329. History. — Charcoal and mineral coal — which are 
the two common forms of carbon — have been known from 
the remotest times of history. Its great importance in the 
daily wants of society, makes it one of the most interesting 
of the elementary bodies, and our interest in it is not dimin- 
ished from the fact that the charcoal and mineral coal which 
we use as fuel, and the ' black lead' of our pencils, are es- 
sentially the same thing with that rare and costly gem, the 
diamond. The three distinct and very dissimilar forms of 
existence which this element assumes, give us one of the 
best examples known of the allotropism (§ 263) of bodies. 
We will very briefly mention the principal characters of the 
three forms of carbon — (1,) the diamond, (2,) graphite or 
plumbago, (3,) mineral coal and charcoal. 

^ 330. The diamond is pure carbon crystallized. It takes 
the forms of the regular system, or first crystalline class, 
{^ 219,) of which the annexed figures are some of its common 
modifications. Its crystalline faces are often curved, as in 




§ 329. Give the equivalent and density of carbon. What is here said 
of carbon ? What three forms of carbon are named ? 



CARBON. 



215 



the second figure. The diamond is the hardest of all known 
substances, and can be scratched or cut only by its own 
dust. The solid angles of this mineral, formed by the 
union of curved planes, are much used, when properly set, for 
cutting glass, which is done with great ease and precision. It 
has a specific gravity of 3'52, and the highest value of any kind 
of treasure. The most esteemed diamonds are colorless, and 
of an indescribable brilliancy, known as the * adamantine 
lustre.' They are often slightly colored, of a yellowish, rose, 
blue, or green, and even black tint. The largest known dia- 
mond belongs to the Great Mogul, and when found weighed 
2769-3 grains, <)r nearly six ounces: it has the form and 
size of half a hen's egg. The most highly valued diamond 
in the world is called the Pitt diamond, and was sold to the 
Duke of Orleans for ^130,000. It weighs less than an 
ounce. This was the gem which Napoleon mounted in the 
hilt of his Sword of State. The diamond is usually found in 
the loose sands of rivers, and is generally accompanied by gold 
and platinum. Its native rock is supposed to be a peculiar flex- 
ible kind of sandstone, called " itacolumite ;" and it is some- 
times found loosely imbedded in a ferruginous conglomerate 
in Brazil. A few diamonds have been found in the United 
States. 

^ 331 . From its high refractive power (^ 56) the diamond is 
supposed to be of vegetable origin. The sun's light seems 
to be absorbed by the diamond, for it phosphoresces most 
beautifully for some time in a dark place, after it has been 
exposed to the sun. It is a non-conductor of heat and elec- 
tricity, and is ver5^ unalterable by any chemical means. It 
is infusible, and not attacked by acids or alkalies. But 
heated to redness in the air, it is totally consumed, and 
the sole product of its combustion is carbonic acid gas, 
which alone is sufficient proof that diamond is pure carbon. 

^ 332. (2.) Graphite or Plumbago. — This form of carbon 
is sometimes improperly called " black lead^^ but it does not 
contain a trace of lead in its composition, and bears no re- 
semblance to it, except that both have been used to mark 
upon paper. 

§ 330. What is the diamond? What forms does it occur under? De- 
Bcribe it as noticed in the text. What is the native source of the dia- 
mond ? § 331. What origin has the diamond been supposed to have, and 
why ? What are its relations to heat, light, and electricity ? How 
affected by chemical means ? What does affect it ? 



216 NON-METALLIC ELEMENTS. 

This peculiar mineral is found in the most ancient rocks, 
as well as with those of a more modern era. It is also fre- 
quently found in company with coal, and is sometimes form- 
ed artificially, as in the fusion of cast iron. It almost always 
contains a trace, and sometimes several per cent, of iron, 
which is however foreign to it ; otherwise it is pure carbon. 
It is very much used for making pencils, and the coarser 
sorts are manufactured into very useful and refractory melt- 
ing pots. The most valued plumbago for the finest drawing 
pencils, has been brought chiefly from the Borrowdale mine 
in Cumberland, England ; but it is a common mineral in this 
country, especially at Sturbridge in Massachusetts, and many 
other places. It is sometimes found crystallized in flat six- 
sided prisms, a form altogether incompatible with that of the 
diamond. It is soft, flexible, and easily cut ; feels greasy and 
marks paper. It is quite incombustible by all ordinary means, 
but burns in oxygen gas, forming only carbonic acid gas, and 
leaving a red ash of oxyd of iron. 

§ 333. (3.) Coal — The vast beds of mineral carbon, 
known to us as anthracite, bituminous coal, brown coal, 
and lignite, are all of them nearly pure carbon. Of the first 
two of these, no country has such abundant and excellent 
supplies as the United States. These accumulations of 
fuel are the remains of the ancient vegetation of the planet, 
which, long anterior to the creation of man, a bountiful Prov- 
idence laid away in the bowels of the earth for his future 
use. Bituminous coal differs from anthracite only in having 
a quantity of bituminous matter united with it, which in 
the anthracite has been driven ofl* by heat and pressure. 

§ 334. Charcoal from wood is the carbonized skeleton of 
the woody fibre which is found in all plants. The best 
charcoal is made by heating sticks of wood in tight iron 
vessels, without contact of air, until all gases and vapors 
cease to be given off. A great quantity of acetic acid, tar, 
and oily matters, with water, are given out, and a jetty black, 
brittle, hard charcoal is left behind, which is a perfect copy 
of the form of the original wood. It is a non-conductor of 
heat, but conducts electricity almost as well as a metal. It 

§ 332. What is plumbago? How found? What use is made of it ? 
How does it crystallize ? What are its physical properties ? How does 
intense heat affect it ? § 333. What is coal ? How does anthracite differ 
from bituminous coal ? § 334. What is charcoal ? How is the best made ? 
What are its powers of conduction ? Is it a changeable substance ? 



CARBOxX. 217 

is a very unchangeable substance, insoluble in water, acids, 
or alkalies, suffers little change from long exposure to air 
and moisture, and does not yield to the most intense heat 
to which it can be subjected. 

^ 335. Charcoal has the property of alsorUng gases to a 
most remarkable degree, at common temperatures. A frag- 
ment of recently heated charcoal, of a convenient size to 
be introduced under a small air-jar over the mercurial cistern, 
will soon take up many times its own volume of air, as 
will appear by the rise of the mercury in the air-jar. In 
this case it absorbs more oxygen than nitrogen, the resid- 
ual air having only eight per cent, of oxygen in it. On 
heating, it again parts with the gas it has absorbed. The 
power of absorption seems to depend entirely on the nat- 
ural elasticity of the gas, and not at all on its affinity for 
carbon. Those gases that are most easily reduced to a 
fluid condition by cold and pressure, are most abundantly 
absorbed by charcoal. Charcoal from hard wood with fine 
pores has this property in the highest degree. Thus char- 
coal from box-wood freshly prepared, will absorb of am- 
moniacal gas 90 times its own volume ; of muriatic acid gas 
85 times; of sulphureted hydrogen 81 times; of nitrous 
oxyd 40 times ; of carbonic acid 32 times ; of oxygen 9 25 
times; of nitrogen 1-5 times; and of hydrogen 1-75 times 
its own volume. 

§ 336. Charcoal also has the power of ahsorhing the had 
odors and coloring principles of most animal and vegetable 
substances. Tainted meat is made sweet by burying it in 
powdered charcoal, and foul water is purified by being 
strained through it. The highly colored sugar syrups are 
completely decolorized by being passed through sacks of 
animal charcoal , (ivory black,) prepared by igniting bones. 
It also precipitates bitter principles, resins, and astringent 
substances from solution. Common ale or porter becomes 
not only colorless, but also in a good degree deprived of its 
bitter principles, by being heated with and filtered through 
animal charcoal. This property is lost by use, and regain- 



§ 335. What is said of its power of absorbing gases ? What gases are 
most absorbed by it 1 What rule regulates this ? Mention some instances 
of the amount of absorption. § 336. How does it affect bad odors and 
vegetable colors? W^hat else does it also remove? To what is this 
analogous 1 

19 



218 NON-METALLIC ELEMENTS. 

ed by heating it afresh. Its powers of absorption seems 
in a good degree similar to that possessed by spongy plati- 
num, (^ 211,) which we have mentioned under the head of 
presence. Hydrogen, in small quantity, is very obstinately 
retained in the pores of charcoal, and water is consequently 
always produced from the combustion of carbon in pure 
oxygen gas. Carbon has a greater affinity for oxygen at high 
temperatures than any other known substance, and for this 
reason it is useful in reducing the oxyds of iron and other 
oxyds to the metallic state, as will be again remarked under 
iron. 



1. Compounds of Carbon with Oxygen. 

^ 337. Carbon unites with oxygen in two proportions, to forni 
carbonic oxyd and carbonic acid, whose composition is thus 
expressed : 

Composition by Weight. 



SymboL Carbon. Oxygen. 

Carbonic oxyd, CO 6 . 8 

Carbonic acid, CO^ 6 16 

§ 338. Carbonic Acid y (CO^.) — History. — This is the sole 
product of the combustion of the diamond or any pure car- 
bon in the air, or oxygen gas. It was first recognized and 
described by Dr. Black, in 1757, under the name o^ fixed 
air. This philosopher proved that limestone and magne- 
sian rocks contained a large quantity of this gas in a state of 
solid combination with the earths, and also that it was freely 
given out in the processes of fermentation, respiration, and 
combustion. 

§ 339. Preparation. — Carbonic acid is easily procured by 
treating any carbonate with a dilute acid. Carbonate of 
lime, in the form of marble powder, is usually employed for 
this purpose ; it is put with a little water into a wide-mouth- 
ed bottle, [b,) (like that used in ^ 306 ;) sulphuric or hydro- 
chloric acid is turned in at the tube funnel, when the gas 
is set free with effervescence, and escapes through the bent 
tube. If it is wished to have the gas dry, it is passed over 



What is said of its affinity for oxygen ? § 337. Name the compounds 
of carbon with oxygen and their composition. § 338. Give the history of 
carbonic acid. § 339. How is it prepared ? How is it dried 1 



CARBON. 



219 

com- 




dry chlorid of calcium in the horizontal tube t, which 
pletely removes 
every trace of mois- 
ture from it. Its 
weight enables us 
to collect it in dry 
bottles (a) by dis- 
placement of air, as 
in the case of chlo- 
rine, (§ 259.) No 
heat is required, 
and the acid is add- 
ed in small suc- 
cessive portions, 
the gas being freely evolved by each addition. If the gas 
is not required dry, the long chlorid of calcium tube may be 
dispensed with. 

This gas can also be collected over the pneumatic trough, 
not being absorbed by water so rapidly but that it may be 
thus managed well enough for experimental purposes. 

^ 340. Properties. — At the common temperature and press- 
ure, carbonic acid is a colorless, transparent gas, with a pun- 
gent and rather pleasant taste and odor. At a temperature 
of 32°, and a pressure of 30 to 36 atmospheres, it is con- 
densed into a clear limpid liquid, not as heavy as water, 
which freezes by its own evaporation into a white, snow-like 
substance. 'We have already described (^ 137) the appara- 
tus and process by which this interesting experiment is 
performed. Carbonic acid is about once and a half as heavy 
as common air, having a specific gravity of 1*524 ; and 100 
cubic inches, therefore, weigh 4726 grains. 

^341. Cold water recently boiled absorbs about its own 
volume of carbonic acid gas, but with pressure much more 
will be taken up, in quantity exactly proportioned to the 
pressure exerted. The solution has a pleasant acid taste, and 
temporarily reddens blue litmus paper. The ' soda water,' 
so much used as a beverage, is usually only water strongly 
impregnated by carbonic acid, the soda being generally omit- 



How may it be collected? §340. What are the properties of carbonic 
acid? At what temperature and pressure does it solidify? What is its 
gravity? § 341. How much of it does water absorb? What is said of 
the solution ? 



220 NON-METALLIC ELEMENTS. 

ted in its preparation. The effervescence of this, as well 
as of small-beer and sparkling wines, is due to the escape 
of this gas. Natural waters have usually more or less of 
this gas dissolved in them ; and some mineral springs, like 
the Saratoga and Ballston springs, and the Sellers waters, 
are highly charged with carbonic acid. 

^ 342. Carbonic acid instantly extinguishes a burning ta- 
per lowered into it, even when mingled with twice or three 
times its bulk of air. Fresh lime-water agitated with this 
gas, rapidly absorbs it, becoming at the same time milky, 
from the production of the insoluble carbonate of lime. In 
this way the presence of carbonic acid is easily detected, 
and this gas distinguished from nitrogen, 

^ 343. Death follows the inspiration of carbonic acid, even 
when largely diluted with air. It kills by a specific poi- 
sonous influence on the system resembling some narcotics, 
and is unlike nitrogen (§ 290) in this particular, which kills 
only by exclusion of air, as water drov^ns. Instances of death 
from sleeping in a close room where a charcoal fire is burning, 
and from descending into wells which contain carbonic acid, 
are lamentably frequent. The latter accident may always 
be avoided by taking the obvious precaution to lower a burn- 
ing candle into the well before going into it, when if the 
candle burns, all may be considered safe ; but its being ex- 
tinguished is certain evidence that the well is unsafe. VVells 
containing carbonic acid may often be freed from it by lowering 
a pan of recently heated charcoal into the well, which will 
soon absorb thirty-five times its bulk of this gas, (§ 335,) 
thus removing the evil. 

^ 344. Numerous natural sources evolve large quantities of 
carbonic acid, particularly in volcanic districts. It abounds 
also, in common with gases to be mentioned hereafter, in coal 
mines ; it is produced abundantly by those explosions, 
which are so often fatal in the mines, and kills by its poi- 
sonous influences those who may escape the explosion. 
The " grotto del cane" in Italy, (dog's grotto,) is a noted in- 
stance of the natural occurrence of this gas. 

It is always present in the air, (§ 300,) being given off by 



Is it found in natural waters ? ^ 342. How does it affect combus- 
tion? What test is there for if? §343. How does it affect life when 
breathed? Is it poisonous? How may these accidents be avoided? 
§ 344. What natural sources of it are named? 



CARBON. 221 

the respiration of all animals, and besides the other sources 
already named, is an invariable product of all common cases 
of combustion. 

All the carbon which plants secrete in the process of their 
development, is derived either from the carbonic acid of the 
atmosphere, which they decompose with the aid of sun-light 
by their green leaves, retaining the carbon and returning 
the pure oxygen to the air ; or it is absorbed by their rootlets 
and then decomposed by the sun's light at the surface of 
the leaf. 

^ 345. Carbonic acid is formed of equal volumes of its two 
constituent gases condensed into one. For this reason the 
air suffers no change of bulk from the enormous quantities 
of this gas which are hourly formed and decomposed on 
the earth. . This acid unites with alkaline bases, forming 
an important class of salts, (the carbonates,) which are all 
decomposed by hydrochloric acid, or in fact any stronger 
acid, with the escape of carbonic acid. 

§ 346. Carbonic Oxyd, (CO.) — Preparation. — This gas is 
produced in several ways. (1.) By passing carbonic acid 
over fragments of coal heated to redness in an iron tube, 
the oxygen gains another equivalent of carbon, and carbonic 
oxyd results. (2.) Oxalic acid, (C2O3, H0 + 2H0,) when 
treated with five or six times its weight of strong sulphuric 
acid, is decomposed, the acid takes the water of the oxalic 
acid, and a gas escapes, which is formed of equal measures 
of carbonic acid and carbonic oxyd. CgOg yield CO and 
COg. The latter (carbonic acid) is absorbed by standing 
over water, or by agitation of the gas with an alkali, and the 
carbonic oxyd is left pure. (3.) Much the best method is 
that recommended by Dr. Fownes, which is to mingle in a 
capacious retort eight or ten parts of sulphuric acid with 
one part of dry finely powdered yellow prussiate of potash. 
The salt is entirely decomposed by a gentle heat, yielding 
an abundant volume of pure carbonic oxyd. 

^ 347. Properties. — This is a colorless, almost inodorous 
gas, burning with a beautiful pale blue flame, such as is 
often seen on a freshly fed coal fire, or wood almost burned 

Is it in the air? Whence do plants get their carbon? § 345. Give its 
composition by volume. What class of salts does it form? § 346. How 
is carbonic oxyd prepared? First ? second ? third ? Which mode is pre- 
ferred ? § 347. What are its properties ? 

19* 



222 NON-METALLIC ELEMENTS. 

away. It has a specific gravity a little less than air, or 
•973; and 100 cubic inches of it weigh 30-20 grains. It 
is not absorbed by water, and does not render lime water 
milky, but explodes feebly with oxygen. It is not irrespi- 
rable, but is even more poisonous than carbonic acid, pro- 
ducing a state of the system resembling profound apoplexy. 
This gas is very largely produced in the process of redu- 
cing iron from its ore in the high furnace. 

Carbonic oxyd is formed of half a volume of oxygen and 
one volume of carbon, or two volumes of carbon and one of 
oxygen condensed into two volumes. 

^ 348. Carbonic oxyd combines with chlorine and some 
other elementary bodies, forming compounds in which il ap- 
pears to act the part of an element. Its union with chlorine 
is produced by the influence of light, and the product has 
been cdXledi phosgene gas. This is a pungent, highly odorous, 
suffocating body, possessing acid properties, and decomposed 
by water. 

2. Other Compounds of Carbon with the Oxygen Group, 

^ 349. The compounds of oxygen and carbon already men- 
tioned are the most important which carbon forms with 
the first class of the non-metallic elements. But there are 
certain others which we will briefly mention. They are — 

Composition by W^eight. 



Chlorid of carbon. 


Symbol. 

CCl 


t — - 
Chlorine. 

35-41 


Carbon. 

6 


Perchlorid of carbon, 


C.CI3 


106-23 


12 


Dichlorid of carbon, 


C,C1 


35-41 


12 


Bromid of carbon, > ^^^^^^-h'^v. 
lodid of carbon, ' J composition 


uncertain. 

Sulphur. 




Bisulphuret of carbon, 


cs^ 


32-18 


6 



^ 350. The chlorids of carbon are obtained from the ac- 
tion of chlorine on a peculiar body formerly called " Dutch 
liquid/'* produced from the union of chlorine, hydrogen, and 

What is its density ? How does it affect life ? In what art is it largely 
produced ? § 348. What compound does it form with chlorine ? What 
is its name ? § 349. What other compounds are named of carbon with 
oxygen ? § 350. What are the chlorids of carbon ? 

* From its being discovered at Harlsem, in Holland. 



siLico?^, 223 

carbon. We shall refer any further mention of these com- 
pounds to the organic chemistry. 

^351. Bisulphuret of carbon is produced by passing the 
vapor of sulphur over fragments of recently prepared char- 
coal, heated to redness in a porcelain tube, which is so in- 
clined that the heavy volatile fluid may run down in vapor 
and be condensed in an ice-cold vessel filled with water. 
This product is redistilled, to purify it. 

§ 352. Properties;. — Bisulphuret of carbon is a colorless 
fluid when pure, but usually has a yellowish tint ; its power 
of refracting light is very remarkable. It has a most dis- 
gusting odor, and boils at 110°. Its density is 1*27, and in 
vapor 268. It dissolves sulphur, phosphorus, and iodine., 
these bodies heing deposited again in beautiful crystals by 
the evaporation of the sulphuret of carbon. It burns in the 
air at about 600° with a pale blue flame. It forms an ex- 
plosive mixture with oxygen, and a combustible one with 
binoxyd of nitrogen. It dissolves easily in alcohol and 
ether, and is precipitated again by water, 

3. Compounds of Carhon with th^^^itrogen Group, 

§ 353. Carhon forms an unimportant compound with phos- 
phorus, but with nitrogen it unites to form one of the most 
remarkable compound bodies known to chemists. This is 
called cyanogen^ and is composed of one equivalent of ni- 
trogen and two of carbon, or NC^. Although a compound, 
it acts in all respects like an element, entering into combi- 
nation with the same energy with which elements unite. 
Its production and properties are, for the sake of simplicity, 
referred to the - organic chemistry, where it can be better 
understood. 

II. SILICON. 

Equivalent, 22*18. Symbol, Si. Density in vapor, [hypothetic 
cal,) 15-29. 

§ 354. Common quartz, or rock crystal and gun-flint, are 
very familiar substances ; these are the compound of sili- 
con and oxygen, known as silica, or silicic acid. Silicon 

§ 351. How is the bisulphuret of carbon prepared? § 352. AVhat are 
its properties ? What does it dissolve? In what is it soluble? § 353. What 
is cyanogen ? How does it act ? Where do we consider it? § 354. Of 
what is silicon the basis? Is it a natural substance ? 



224 NON-METALLIC ELEMENTS, 

is, however, a substance very rarely seen, even by chemists, 
because it never occurs in nature, and is very difficult to 
prepare. Silica, its compound with oxygen, is, next to 
oxygen, the most abundant, and one of the most important 
substances known. It is calculated that it forms one-sixth 
part of the crust of the globe. 

^ 355. Preparation of Silicon. — Silica retains its oxy- 
gen so powerfully that it is very difficult to separate it and 
leave the pure silicon. Silicon may be procured, however, 
by an indirect process, which is to decompose the double 
fluorid of silicon and potassium, (2SiF3 + 3KF.) This is 
a white powder, like starch, and very sparingly soluble in 
water. To decompose this, it is mixed with about its own 
weight of the metal potassium, cut in 
small pieces, and put in a test tube of 
hard glass, which is then heated over a 
lamp. As soon as the tube is heated 
on the bottom to redness, a vivid ignition 
is seen to take place, and to spread 
through the whole mass. The residue 
%fterthis ignition, when cool, is treated 
with water, which dissolves all the fluo- 
rid of potassium that has been formed in the process, leaving 
behind the silicon. Thus the (2SiF3 + 3KF) acted on by 
6K give 9KF and2Si. 

§ 356. Properties. — Silicon is a dark nut-brown powder, 
without metallic lustre, and a non-conductor of electricity. 
Heated in air or oxygen it burns, forming silica. If heated 
in a close vessel, it shrinks and becomes more dense. Be- 
fore ignition it is soluble in hydro-fluoric acid, but after this 
it is insoluble, and is incombustible in the air or oxygen gas. 
It seems then to resemble the graphite variety of carbon. 
These two distinct conditions of silicon are analogous to and 
probably connected with the two states to be presently no- 
ticed in which silica occurs. This element has been often 
called a metal, and named accordingly silicium ; but if power 
to conduct electricity, and the possession of a metallic lustre, 
are attributes of a metal, silicon has no claim to be so class- 
ed. Its real analogies are all with carbon. 

How abundant is silica ? § 355. How is silicon prepared ? Give the 
reaction. § 356. What are its properties? How does heat affect it? 
What two states of it are noticed ? To what are these analogous? Why 
Bot consider it a metal? 




SILICON. 



225 



Compounds of Silicon with the Oxygen Group. 

■^ 357. The known compounds of silicon are not numer- 
ous ; those mentioned in this section are — 

Composition. 



Silicic acid, (silica,) 


Symbol. 

S1O3 


r 
Silicon 

22-18 


Oxygen. 

24 

Chlorine. 


Chlorid of silicon, 


SiCl3 


22-18 


106-23 

Bromine. 


Bromid of silicon, 


SiBr3 


22-18 


234-78 

Fluorine. 


Fluorid of silicon, 


SiF3 


22-18 


56 10 


Sulphuret of silicon, 


SiS3(probably)22-18 


Sulphur.. 

66-54 



The similarity of composition in these bodies is a re- 
markable circumstance, as will be seen at a glance by in- 
specting their formulas. 

^ 358. Silicic acid or Silica, (SiOg,) — This oxyd of sil- 
icon exists abundantly in nature in the form of rock crystal, 
agate, common uncrystallized quartz, silicious sand, &c. ; it 
also enters largely into combination with other substances 
to form the rock masses of the globe. It is a very hard sub- 
stance, easily scratching glass, and is difficult to reduce to a 
powder; its specific gravity is 2-66. It is infusible alone., 
except by the power of the compound blowpipe. It dis- 
solves with effervescence in fused carbonate of soda or pot- 
ash ; the effervescence being due to the escape of carbonic 
acid from the alkali, which is replaced by the silicic acid. 
No acid (except the hydrofluoric) has any effect on silica. 
When in its finest state of division it is still gritty to the touch 
or between the ^eeth. 

^ 359. Silica is known in two very unlike conditions — its 
insoluble or common condition, and its soluble or hydrous 
state. When silica is dissolved in a fused alkali, and theu 
again this silicated alkali in a strong acid, as the hydrochlo- 
ric, we obtain on evaporating the solution to a small bulk, a 
tremulous gelatinous mass, which is soluble silica. If an 
excess of alkali is used, the silicate formed is soluble ia 
Avater, and is sometimes called the ^ liquor of flints.^ If this 
soluble silica is dried, it is again reduced to its insoluble 

§ 357. What compounds of silicon are named ? § 358. What is silicic 
acid? Give its properties. What dissolves it? §359. What two milike 
conditions of silica are named ? How is the sohible condition produced ? 



226 NON-METALLIC ELEMENTS. 

condition. Most natural waters contain sonie small portion 
of soluble silica ; it has been often seen in this state in 
mines ; and on breaking open silicious pebbles, the central 
parts are sometimes semi-fluid and gelatinous. The hot 
waters of the great geysers in Iceland, and of other hot 
springs, also dissolve large quantities of silica, probably 
aided by alkaline matter. A great deal of the silica which 
is commonly known as agates, chalcedony, carnelian, &c. 
has been deposited from the soluble state. It is in this con- 
dition, no doubt, that silica enters the substance of many 
vegetables, as, for instance, the reeds and grasses, which 
have often a thick crust of deposited silica in their bark. 
It also produces most beautiful petrifactions of natural ob- 
jects, as corals, shells, and many vegetables, completely re- 
placing the organic matters, and turning them into solid 
quartz or elegant chalcedony and agates. 

§ 360. The uses of silica in the arts are very important. 
It is the basis of all glass, being fused with alkalies to form 
this useful and beautiful substance, (see glass and pottery,) 
and also of porcelain and all kinds of potters' ware. In 
chemistry its uses are chiefly confined to certain analytical 
operations of no importance to our present object. 

§ 361. It is called an acid, from the power it has of acting 
the part of a powerful acid at high temperatures. At ordi- 
nary temperatures its insolubility renders its acid properties 
insensible to all our usual tests for acids. When by a 
sufficient temperature it is rendered soluble, we see 
its acid character very distinctly in the ease with which it 
completely saturates the most powerful alkalies. 

§ 362. Chlorid of silicon is formed by passing a current of 
dry chlorine gas over silicon heated to redness in a tube of 
porcelain or glass ; or, more simply, by employing, in place 
of silicon, the finely powdered silica mixed with powdered 
charcoal in the same tube, and treated in the same man- 
ner. The carbon takes the oxygen of the silica at the high 
temperature, and the chlorine unites with the silicon to form 
a very volatile chlorid of silicon, which is condensed in a 
cold receiver, while the excess of chlorine, and the carbonic 
oxyd form,ed in the process, escape as gases. The 

How do we find it in nature? What function does it discharge? 
<§ 360. What are the uses of silica? § 361. Why is it called an acid? 
Why are its acid properties concealed? § 362. How is chlorid of silicon 
formed? What are its properties ? 



SILICON. 227 

cWorid of silicon is a colorless liquid, denser than water, and 
boils at 124°. Water decomposes it, forming hydrochloric 
acid and silica. 

There is a bromid of silicon possessing the same proper- 
ties and formed in an exactly similar manner. 

§ 363. Fluorid of silicon, (fluo silicic acid ) — The affinity 
existing between fluorine and silicon is one of the strongest 
known to chemists. We have already mentioned this while 
speaking (^ 279) of fluorine. Fluorid of silicon may be 
procured by heating a mixture of powdered fluor-spar and 
quartz with strong oil of vitriol : 

Fluor-spar, Silica. Snl. acid. Sul. lime. Water. Fluorid silicon. 

3CaF+Si03+3(S03,HO)=3(CaO, S03)-4-3HO-i-SiF3. 

Being rapidly absorbed by water, it must be collected over 
mercury. It forms dense white vapors with the moisture 
of the air, as soon as it comes in contact with it. 

^ 364. Properties. — This is a dense, colorless gas, 
having a specific gravity of about 360, air being 1, and it 
has lately been rendered fluid by Dr. Faraday, with a cold 
of 160° below zerO; and a pressure of about nine atmos- 
pheres. When this gas is passed into a vessel of water, 
it is decomposed, each bubble becomes incrusted in a 
shell or sack of pure silica, and retains its form more or 
less as it rises through the water, which soon becomes 
nnilky, from the quantity of finely divided silica suspended 
in it. Meanwhile the water becomes a solution of hydro- 
fluosilicic acid, which is formed from the decomposition of 
one-third of the fluorid of silicon, giving silica and hydro- 
fluoric acid, which last unites with the remaining fluorid of 
silicon, and dissolves in water: or 2(SiF3) + 3HF. The 
fluo-silicic acid gas should not be passed directly into water, 
but the tube should dip under the surface of a portion of 
mercury in the bottom of the bottle holding the water : if this 
precaution is neglected, the open end of the tube soon be- 
comes plugged up with silica, and the gas bottle m^y burst. 
This acid solution is decomposed by heat. It forms almost in- 
soluble salts (double fluorids) with the metals potassium and 
sodium, and hence is of much value in separating these sub- 
stances from their solutions. 



§363. How is fluorid of silicon formed? Give the reaction on the 
black-board. Is it absorbed? § 364. Give its properties. How does it 
behave m contact with water ? What reaction takes place ? What 
caution is required ? 



228 NON-METALLIC ELEMENTS. 

§ 365. Silicon^ when heated with sulphur, unites w4th it, 
forming a sulphuret, which is a white earthy compound, 
(SiS 3 .) It is decomposed by water into silica and sulphureted 
hydrogen. 

III. BORON. 

Equivalent, 1090. Spnhol, B. Density in vapor, {hypothet- 
ical,) 751. 

§ 366. The only compound of boron commonly known 
is borax, a salt much used in the arts. Boracic acid (its 
compound with oxygen) is found in the waters of certain 
lagoons or lakes in Tuscany, from which large quantities of 
it are introduced to commerce. This acid, accompanied by 
sulphur and selenium, is also sublimed among the volcanic 
products of the volcanos at the Lipari islands, and in other 
similar places. 

§ 367. Boron is prepared by a process very similar to that 
which produces silicon. The double fluorid of boron and 
potassium being treated with potassium in an iron vessel 
heated to redness, give us KF, BF3 + 3K = 4KF + B. The: 
boron remains as a dark olive-green powder, after the 
soluble fluorid has been dissolved out by wate'r. Heated in 
air to about 600°, it burns brilliantly, producing boracic acid. 
It does not conduct electricity, is insoluble in water and all 
other neutral fluids. Heated out of contact with air, it suf- 
fers no change. It is easy to see how similar these char- 
acters are to those possessed by carbon and silicon. 

Compounds of Boron icith the Oxyge^i Group. 

§ 368.. The compounds of Boron mentioned under this 
head are 





Symbol.- 

BO3 
BCI3 
BFI3 
BS3 


Composition by weight. 


Boracic acid, 
Chlorid of boron, 
Fluorid of boron, 
Sulphuret of boron, 


Boron. Oxygen. 

10-90 24 

Chlorine. 

10-90 106-23 

Fluorine. 

10-90 56-10 

Sulphur. 

10-90 48-27 



§ 365. What is the sulphuret of silicon? § 366. Give the equivalent 
and symbol for boron. How is it found associated in nature ? § 367. How 
is boron prepared? What are its properties? To what is it likened? 
§ 368. Name the compounds of boron in this section. - 



I 



HYDROGEN. 235 

not well vmderstood. It was associated witli oxygen and 
chlorine, because it was supposed to bear the same relations 
to hydrochloric acid that oxygen bears to sulphuric and 
chloric acids. Dr. Kane was the first to insist on the highly 
electro-positive natureof hydrogen, and to prove to the satis- 
faction of chemists that this gaseous body was in reality 
more nearly allied to iron, zinc, copper, and manganese, than 
to any other class of bodies.* He showed that the compounds 
of hydrogen with oxygen, chlorine, iodine, sulphur, &c., 
were almost universally electro-positive in combination, and 
possessed basic characters, derived from the pre-eminent 
electro-positive energies of hydrogen itself. It is now the 
belief of nearly all philosophical chemists, that hydrogen is 
most closely allied to the metals, particularly to zinc and 
copper ; that the chlorids, iodids and fluorids of hydrogen, 
although they possess the characters which we assign 
to acids, resemble in all important respects the chlorids, 
iodids, &c., of the metals above mentioned ; that in 
fact hydrogen is a metal, exceedingly volatile, probably 
standing in that respect in the same relation to mercury 
that mercury does to platinum, but still possessed of all 
truly chemical peculiarities of the metallic state, and no 
more deprived of the common-place qualities of lustre, hard- 
ness, or brilliancy, than is the mercurial atmosphere which 
fills the apparently empty space in the barometer tube.f 
The vapor af mercury, and of other volatile metals, is 
also a non-conductor of heat and electricity ; but we cannot 
on this account deny their metallic character. We must 
not forget that hydrogen may yet, by sufficient cold and 
pressure, be made solid or fluid, when doubtless we shall 
see its resemblance in physical, as well as we now do in 
chemical characters, to the metals. The propriety of giving 
hydrogen the place in our classification which it occupies, 
will now be more apparent to those who have usually seen 
it placed next to oxygen. 



To what is it compared ? What is the present opinion of chemists 
about hydrogen? What analogous cases have we in the volatile metals? 



* Dr. Hare, more than 20 years since, expressed the opinion tliat hy- 
drogen was an a3riform metal, 
t Dr. Kane's Elements, page 409, English edition. 



236 NON-METALLIC ELEMENTS. 



2. Compounds of Hydrogen with the Oxygen Group, 

§ 383. Compounds of Hydrogen with Oxygen. — There 
are two known compounds of hydrogen with oxygen, viz : 

Composition by weight. 



Hydrogen. 


Oxygen. 


1 


8 


1 


16 



Symbol. 

Water, (the oxyd of hydrogen,) HO 
Binoxyd of hydrogen, HO^ 

The first of these is, all things considered, the most re- 
markable compound known, whether we contemplate it in 
its purely chemical relations, or in reference to the wants of 
man and the present condition of the globe. 

§ 384. Water, — The reader has already been made 
familiar with the composition of water, as formed by the union 
of two volumes of hydrogen and one of oxygen. Frequent 
mention has been made of it in the foregoing pages of this 
virork, as an illustration of the principles of combination and 
decomposition. We cannot properly understand the produc- 
tion of hydrogen by any process, without studying at the 
same time the constitution of water. In examining the com- 
pounds of hydrogen and oxygen, as in all other chemical in- 
vestigations, we can pursue the subject either analytically or 
synthetically. That is, we can either form the compounds 
by the direct union of the elements, or we can decompose 
these compounds, and thus gain a knowledge of their con- 
stitution. We will do both, and will first attend to 

^385. The Decomposition of Water. — The simplest case 
of the decomposition of water is that where metallic potas- 
sium is employed, which is directly oxydized by the water, 
hydrogen being evolved. The reaction is K+HO = KO + H, 
which last is given off. 

§ 386, The voltaic decomposition of water has already 
been described, (§ 234,) and we need not repeat it here. It 



§ 383. What are the compounds of hydrogen and oxygen ? Give their 
composition. § 384. What is said of the constitution of water ? How- 
can we proceed in studying the compounds of hydrogen and oxygen ? 
§ 385. What is the simplest case of the decompositioxi of water? 



COMPOUNDS OF HYDROGEN. 



237 




is, however, by far the most satisfactory means of decom- 
position which we possess, since both 
elements of the water are evolved in a 
pure form and in exact atomic propor- 
tions. In fact this is a complete ex- 
perimentu7n crucis^ being both analysis 
and synthesis ; for w^c may so arrange 
the single tube apparatus, that the mix- 
ed gases from the electrolysis of water 
may be fired by the ignition of the wires, 
as soon as a sufficient volume of the 
mixture has been collected. A com- 
plete absorption follows the explosion, 
and the gases again go on collecting. 
The oxygen which is dissolved in water 
from the air, always makes this exper- 
iment, when accurately performed, 
seem to show a very slight excess in the oxygen. 

^ 387. The decomposition of water hy heat in the manner 
here figured is one of the best methods of analyzing water, 
both from its satisfactory results, and its cheapness and ease 
of accomplishment. An iron tube, (as a gun barrel, c,) or a 
tube of porcelain, is laid 
horizontally over a fire, or 
heated in a furnace to full 
redness. The tube con- 
tains clean turnings of 
iron, or better, a bundle 
of clean iron wire of 
known weight*. A small 
retort {a) holding a little 
water is boiled by a spirit lamp at the moment when the 
iron is at full red heat ; the vapor of the water coming into 
contact with the heated iron, is decomposed, the oxygen is 
retained by the iron, forming oxyd of iron, and the hydro- 
gen is given off from the tube,/, which may be made to con- 
duct it, either to the pneumatic trough, or to a gas-holder like 
the one already figured, (^ 257.) For every eight grains of 




§386. What is the voltaic mode of decomposition? §387. Describe 
the method of decomposing water by heat. What is the reaction in 
this case ? How much hydrogen do we get for eight grams of gain in 
the iron ? 



238 NON-METALLIC ELEMENTS. 

weight acquired by the iron, 46 cubic inches of hydrogen, 
weighing one grain, have been evolved. 

^ 388. The iron in this case is evidently substituted for 
the hydrogen, taking its place with the oxygen to form the 
oxyd of iron, while the hydrogen is set free. The oxyd of 
iron resulting from this action is the same black oxyd which 
the smith strikes off in scales under the hammer, being a 
mixture of protoxyd and peroxyd. This case of affinity is 
an interesting one, because it is seemingly reversed when, 
under the same circumstances, we pass a stream of hydro- 
gen over oxyd of iron, by means of which the iron is 
reduced to the metallic state, and water is produced. It will 
be remembered that we cited this instance, (§ 210,) while 
speaking of the influence of quantity of matter in determin- 
ing the nature of the chemical changes which might take 
place among bodies. 

^389. The decomposition of water by zinc or iron in the 
ordinary mode of procuring hydrogen can now be satisfac- 
torily explained. As already stated, dilute sulphuric acid is 
added to fragments of zinc, or to iron filings, and hydrogen 
gas is given off abundantly with effervescence. The action 
continues until either the zinc or acid is all consumed, or 
until there is no longer water enough to dissolve the result- 
ing sulphate of zinc. Thus we take 

Zn+S03 + H0, and we obtain H + (S03 + ZnO.) 

In other words, the zinc has taken the place before occupied 
by hydrogen, while the oxygen of that atom of water has 
united with the zinc, to form oxyd of zinc* The acid dis- 
solves this oxyd as fast as it is formed, thus making a con- 
stantly renewed surface of clean metal. The water serves 

§ 388. What is the action of the iron in this case? What oxyd is 
formed? §389. How is the decomposition of water by zinc explained? 
Give the reaction. How is it in case we employ hydrochloric acid? 
(Note.) What does the acid do, and what the water ? How do the elec- 
trical relations affect this change ? 

* We can state this reaction in much more simple terms, by employing 
hydrochloric acid in place of sulphuric acid : we have then 

Hydrochloric acid -j- zinc. Hydrocren -f- chlorid of zinc. 

HCl+Zn and obtain H-f ZnCL 

In this case there is no oxydation, for the same change is made when 

dry hydrochloric acid is used, and consequently no compound containing 

oxygen is present. 



COMPOUNDS OF HYDROGEN, 239 

to dissolve the sulphate of zinc as fast as it is formed. Zinc 
and iron decompose water even without the aid of an acid, 
but only with great slowness, and the action ceases as soon as 
the metal is covered by the coating of the oxyd thus form- 
ed, which protects it from further corrosion. A dilute acid re- 
moves this coating of oxyd, and also aids, no doubt, in estab- 
lishing such electrical relations as to make the zinc highly 
electro-positive. That this is the fact, seems highly prob- 
able, because pure zinc is hardly affected by dilute acids, 
and we have already noticed the effects of amalgamation 
(§ 160, note) in rendering the zinc incapable of decomposing 
water. 

^ 390. It was formerly said that the presence of an acid 
in water with zinc ' disposed^ the zinc to decompose the 
water, because the acid was ready to take up the oxyd as 
soon as formed. This was called a case of " disposing affin- 
ity." But there can be no oxyd of zinc to exert this influence 
on the acid, until the water is decomposed ; so that the idea 
that the acid " disposed" the zinc to decompose the water 
is quite futile. We find a much simpler and more probable 
explanation in the foregoing section. 

^391. The recomposition or formation of water from its 
elements may be effected in a variety of ways. A mixture 
of oxygen and hydrogen gases will never unite under ordi- 
nary circumstances of temperature, &c.; but the passage of 
an electric ^park through them, or the application of red- 
hot flame, or intensely heated wire, will produce an explo- 
sive union, destructive to the containing vessel, unless the 
gas is in extremely small quantities. 

If this mixtur^e is made in exact atomic proportions, and 
the gases are pure, the result of the explosion will be a com- 
plete absorption ; but usually one of the gases is in slight 
excess. 

§ 392. This explosion may be safely made in a tube of 
very strong glass, and holding only one or two cubic inches 
of the mixed gases. This tube is usually graduated into 
parts of a cubic inch, and it is fitted for the passage of the 
spark with two wires which come near to each other, but do 
not touch. A gas pistol of metal, (a,) like the figure, gives a 
perfectly safe method of performing this experiment, being 

§ 390. What is said of disposing affinity ? § 391. How is tho recompo- 
sition of water effected ? 



240 



NON-METALLIC ELEMENTS. 




filled with the mixed gases and stopped with a cork, {o ;) a 
smart explosion follows the application of the spark, and 
the cork is forcibly driven out by the expan- 
sion of the uniting gases, accompanied by flame. 
A bladder filled with the mixed gases in 
atomic proportions, will be blown into shreds 
with a deafening explosion, by the application 
of a match to a pin-hole made in its side. 
Soap-bubbles filled from a bag of the explo- 
sive mixture will, from their lightness, rise 
rapidly, and may be exploded by a match or can- 
dle. In all these cases the sole result is the production of 
water ; but, being in the form of vapor, it escapes unseen. 

^ 393. The formation of v: at er may he proved hy burning a 
jet of hydrogen in a dry vessel of oxygen, or even of com- 
mon air. For this purpose the jet of the compound blow- 
pipe may be introduced into a large dry globe of glass, and 
the supply of the two gases regulated by the stop-cocks. 
The interior of the globe is immediately bedewed with the 
vapor of water produced in the combustion, which rapidly 
collects in drops on the sides of the vessel, and runs down 
to the bottom. No question in science has excited more 
inquiry and research, than the constitution of water. Re- 
peated trials, both analytical and synthetical, often on a most 
liberal scale and long continued, have been made to prove 
it ; and the uniform result of the best experiments has been, 
that 8 parts by weight of oxygen require 1 part by weight 
of hydrogen to form 9 parts of water, and that 2 volumes of 
hydrogen saturate 1 volume of oxygen. 

§ 394. Hydrogen is frequently employed in eudiomeiry, or 
in the analysis of gases. For this purpose a known vol- 
ume of hydrogen is mingled with a given amount of the gas 
to be analyzed, and the mixture is exploded by electricity 
in a graduated tube of glass, or some other similar form 
of apparatus. The figure of a very good form of eudiometer 
invented by Dr. Ure is here annexed. It is a U tube 
of stout glass ten or twelve inches long, the shorter limb of 



§ 392. How may this conveniently be done ? Name some other simi- 
lar experiments. § 393. How is the water produced in these experiments 
made manifest ? Describe the experiment. § 394. How is hydrogen 
used in eudiometry ? 



COMPOUNDS OF HYDROGEN. 



241 




which is closed, and graduated into decimals of a cubic inch. 
Two wires of platinum, for the passage 
of the spark, are fused into the glass 
near the top. When it is to be used, it 
is filled with dry mercury, by placing it 
horizontally in the mercury trough, and a 
convenient portion of the mixture of the 
gas to be examined with hydrogen is 
then introduced. The thumb is pla- 
ced over the open end, and by adroit 
management all the mixture is transfer- 
red to the closed end of the tube, and 
by forcing out a portion with a rod, thrust 
into the open end, the mercury is made to 
stand at the same level in both limbs. 
These adjustments being made, the 
whole bulk of the mixture is read on the graduation, and 
while the thumb is firmly held over the open end of the tube, 
an electrical spark is made to explode the gases. The air 
between the thumb and the mercury acts like a spring to 
break the force of the explosion ; and afterwards, on remov- 
ing the thumb, the weight of the atmosphere forces the mer- 
cury into the shorter leg, to supply the partial vacuum oc- 
casioned by the union of the gases. Proper allowances being 
made for temperature and pressure, the quantity of residual 
gas is read on the graduation, and a calculation can then be 
made of the amount of oxygen present. If the gas contains 
carbon, carbonic acid would be formed, and must be absorbed 
by an alkali. 

Dr. Hare has described a very convenient eudiometer, 
which he calls a *' sliding-rod eudiometer," in which the 
volumes of the gases are read by the divisions on a sliding- 
rod of metal moving in a tight collar, and the measured por- 
tion of mixed gases is exploded by a platinum wire ignited 
by galvanism, in an attached glass vessel. 

^ 395. The union of oxygen and hydrogen can however 
be effected slowly and quietly without any explosion, or vis- 
ible combustion. This may be done by passing the mixed 
gases through a tube heated below redness, when combi- 



Describe Ure's eudiometer. How is it used? What is Hare's eudiom- 
eter? § 395. How is the quiet union of hydrogen and oxygen accom- 
plished ? 

21 



242 



NON-METALLIC ELEMENTS. 




ond fig.) 



nation takes place, without explosion. This result is ac- 
complished at a still lower temperature, if the tube contains 
coarsely powdered glass or sand. We see in this case the 
operation of that remarkable power of surface (§ 211) once 
or twice alluded to before ; and we will now mention a still 
more remarkable instance of the same action. 

^ 396. Power of platinum in promoting the union of Oxy- 
gen and Hydrogen. — Professor Dobereiner of Jena, many 
years ago, (in 1824,) informed us that platinum in the state 
of fine division known as spungy platinum, would cause an 
immediate union of these gases. The common instru- 
ment employed for lighting tapers is made by 
taking advantage of this principle. A little spungy 
platinum is formed into a ball, like the annexed 
figure, and mounted on a ring of wire which slips 
within the cup [d ) on top of the gas-holder, {a, sec- 
The gas is generated by the action of dilute acid 
in the outer vessel [a) on a lump of zinc {z) 
hanging in the inner vessel, (/,) and is let out 
at pleasure by the cock, (c,) issuing in a stream 
on the spungy platinum. The latter is 
at once heated to redness by the stream of 
hydrogen, which is condensed within its pores 
to such a degree as to be forced to combine 
with a portion of oxygen, always present in 
the spunge by atmospheric absorption. The 
union of these gases is always attended by 
intense heat, and, as a consequence, the pla- 
tinum at once glows v/ith redness, and the hydrogen is infla- 
med. After some time the spunge loses this property to a 
certain extent, but it is again restored by being well ignited. 
When the spungy platinum is mixed with more or less 
clay and made into balls, its effects are less intense, and 
such balls are often used in analysis to cause the gradual 
combination of gases. 

§ 397. Dr. Faraday has shown, however, that it is by no 
means essential that the platinum should be in the spungy 
form in order to effect the result. Clean slips of ijlatinuin 
foil, and even of gold and palladium, can produce the union 
of hydrogen and oxygen. For this purpose the platinum is 
cleaned in hot sulphuric acid, washed thoroughly with pure 

§ 396. How does platinum produce this result ? What common instru- 
ment illustrates this? In what state is the platinum? How is the heat 
produced ? §397. What has Dr. Faraday shown about platinum? 




COMPOUNDS OF HYDROGEN. 243 

water, and hung in a jar of the mixed gases. Combination 
then takes place so rapidly as to cause at every instant a 
sensible elevation of the water in the jar. If the metal is 
very thin, it sometimes becomes hot enough during the pro- 
cess of combination to glow, or even to explode the gases. 

^ 398. The same effect of platinum in causing combina- 
tion is seen in other bodies besides oxygen and hydrogen. 
Several mixtures of carbon gases will act with platinum in the 
same way, and the vapors of alcohol or ether .^^ -— — 
may be oxydized by a coil of platinum wire x '^ J^ 

hung from a card in a wine-glass containing ^^'W'liJMifm 
a few drops of either of these fluids. The \ W/l^W 
coil of wire is heated to redness in a lamp, \ Wm 
and while still hot is hung in the glass ; it \ ff 
then retains its red-hot condition as long as ^^^ 

any vapor of ether or alcohol remains. In ]%_ 

this case, only the hydrogen of the ether or (^^ZlS^^ 
alcohol is oxydized, and the carbon is unaf- ^=*=5=:====»**^ 
fected ; a peculiar irritating odor of acetic ether is given off, 
which affects the nose and eyes unpleasantly. Little balls 
of platinum spunge suspended over the wick of an alcohol 
lamp will glow after the lamp is extinguished. This is a 
common toy at the instrument-makers. 

^ 399. Compound or oxyhydrogen blowpipe. — The heat 
produced by the combustion of oxygen and hydrogen, in 
atomic proportions, is the most intense that can be obtained 
by artificial means. Dr. Hare of Philadelphia was the first 
who succeeded in forming an instrument to burn these gases 
together safely, which Professor Silliman called " the com- 
pound blowpip'e." The invention was afterwards appropri- 
ated by Dr. Clarke in England. The arrangement is such 
in this instrument, that the two gases are brought from sep- 
arate gas holders, by flexible tubes, so as to deliver at the 
same time two volumes of hydrogen, and one of oxygen 
gas, the hydrogen gas tube terminating in a hollow cylindri- 
cal jet, (Daniell,) inside of which passes the jet of oxygen gas. 
Thus arranged, the gases come in contact only at the moment 
of combustion, and all danger of explosion is avoided. 

The flame from the compound blowpipe difters from the 

How is it cleaned? What follows its immersion in tlie mixed erases? 
§ 398. What further case of surface action is instanced 1 § 399. What 
is the compound blowpipe, and by whom invented ? How is it arranged ? 



244 



NON-METALLIC ELEMENTS. 




common flame of a lamp or candle, by being, so to speak, a 
solid cone of ignited aerial matter , instead of being (like a 
flame) ignited only on the outside ; (see flame and combus- 
tion.) Numerous modifications of the compound blowpipe 
are in use, the most important of which we will barely men- 
tion. That most generally adopted, and the most safe, is to 
store the gases in separate holders, and bring them, as just 
mentioned, by distinct tubes to a common jet. 

^ 400. Two hags of gu7n- elastic cloth answer very well 
to store the two gases, and are fit- 
ted after the fashion of a bellows, 
with a hinge on one side. This is 
the mode usually adopted in the ar- 
rangement of the hydroxygen mi- 
croscope. The eflects of the com- 
pound blowpipe may also be safely 
produced by passing a stream of ox- 
ygen from a gas-holder through the 
flame of a spirit-lamp, (w;,) as is 
seen in the annexed figure. The jet 
is regulated by the cock, (/,) and the 
lamp flame supplies the hydrogen. 
^ 401. The mixed gases in atomic proportions are some- 
times forced by a condensing syringe into a very strong me- 
tallic box, from which they issue by their own 
elasticity. To prevent the danger of an ex- 
plosion, a contrivance is employed called 
" Hemming's safety tube," which is a brass 
tube six or eight inches long, filled with fine 
brass wire, closely packed, and having a co- 
nical rod of brass forcibly driven into their 
centre, by which the wires are very closely 
crowded together. This forms in fact a great 
number of small metallic tubes, through which 
the gas must pass. It is a property of such 
small tubes entirely to arrest the progress of 
flame, as we shall see under the compounds 
of carbon and hydrogen. The jet is screwed 
to one end of this tube, and the other end is 
connected with the holder of the mixed gases. 

How does its flame differ from that of a common lamp ? § 400. What 
arrangements are adopted for this instrument ? How may oxygen be em- 
ployed alone ? §401. How are the mixed gases used alone? What 
is Hemraing's tube of safety? 




COMPOUNDS OF HYDROGEN. 245 

Several severe explosions, it is said, have occurred, even with 
all these precautions ; so that if the mixed gases are used 
at all, it should be only in a bag or bladder, the bursting of 
which can be attended with no danger. 

^ 402. The effects of the compound blowpipe are very re- 
markable. In the heat of its focus the most refractory 
metals and earths are fused or dissipated in vapor. Plati- 
num, which does not melt in the most intense furnace 
of the arts, here fuses with the rapidity of wax. By the 
adroit management of the keys, which a little practice soon 
teaches, we can either reduce metallic oxyds, or oxydize 
substances still more highly. The flame of the mixed 
gases falling on a cylinder of prepared lime, adjusted to 
the focus, produces the most intense artificial light known. 
This is sometimes called the " Drummond light." It is 
now extensively employed in distant night signals, and can 
be seen further at sea than any other light. Much use is 
also made of it as a substitute for the sun's light in optical 
experiments, which is a most important fact in the experi- 
mental sciences. All optical results can be more conven- 
iently shown by the oxyhydrogen light, than by the sun ; 
and thus many instructive experiments can be exhibited to 
an evening audience, or on a dark day. The galvanic focus 
alone, among artificial sources of light, equals it. 

3. Natural and Chemical History of Water. 

§ 403. Water when pure is a colorless, inodorous, tasteless 
fluid, which conducts heat and electricity very imperfectly. 
It refracts light powerfully, and is almost incapable of com- 
pression. Wq have made so much use of water as an ex- 
ample, in illustration of the laws of heat, Sic, in the first 
part of this volume, that the reader must already be familiar 
with many of its attributes. Its greatest density, it will be 
remembered, (§ 86,) is found to be at 39° 5, or, more exactly, 
39° 83. It is the standard of comparison (§ 38) for all 
densities of solids and fluids. In the form of ice, its density 
is 0*92, and it freezes at 32°. One imperial gallon of water 
weighs 70,000 grains, or just ten pounds. The American 

§ 402. What are the effects of the compound blowpipe ? What is the 
" Drummond light?" What use is made of it? §403. Give the prop- 
erties of pure water» Of what is it the standard ? How much does 
the imperial gallon hold ? How much the American ? 

21* 



246 NON-METALLIC ELEMENTS. 

Standard gallon holds, at SQ'' 83' Fabr., 58,372 American 
troy grains of pure distilled water. One cubic inch at 60^ 
and 30 inches barometer, weighs 252-458 grains, which is 
815 times as much as a like bulk of atmospheric air. One 
hundred cubic inches of aqueous vapor, at 212° and 30 
inches barometer, weigh 14-96 grains, and its specific grav- 
ity is 0-6202. 

^ 404. Water boils under ordinai'y circumstances at 212° ; 
but we have seen (^ 119) that its boiling point was very 
much affected by the nature of the vessel. Since the first 
part of this volume was printed we are informed by Mr. F. 
Donney, that water may be heated even to 275°, provided it 
be perfectly free from air, and that this is the case even in a 
vacuum.* It evaporates at all {^ 129) temperatures. 

^ 405. Pure water is never found on the surface of the 
earth, for the purest natural waters contain small quantities of 
earthy or saline matters which they have dissolved from the 
rocks and soil. Moreover, all good water — that which is 
fit for the use of man — has a considerable quantity of car- 
bonic acid and atmospheric air dissolved in it, and with- 
out which it would be flat and unpalatable. Many mineral 
springs, beside the saline matters they hold in solution, are 
highly charged with sulphureted hydrogen, carbonic acid 
gas, and other gases derived from decomposition, in the strata 
through which they pass. In the appendix is given a table 
containing several minute analyses by the author of natural 
waters, taken from some of the purest lakes and rivers in 
the United States ; and also others, by different chemists, of 
sea-water and the waters of saline springs. A glance at this 
table will show that water is a great solvent, and that it 
must be the means of conveying into the systems of plants 
and animals those inorganic substances v/hich are always 
found to be among their essential constituents. 

§ 406. Pure water can he procured only by distillation, 
and it is a substance of such indispensable importance to 

WTiat is the weight of a cubic inch of water ? § 404. What is the 
boiling point of water? What departures from this law are named? 
§ 405. What does common water contain? Why is it never pure ? What 
conclusion is drawn from the analyses in the appendix ? § 406. How is 
pure water obtained? 

* American Journal of Science, vol. ii, (2d series,) page 257. 



COMPOUNDS OF HYDROGEN. 247 

the chemist, that every well furnished laboratory is provided 
with means for its abundant preparation. A copper still, well 
tinned, and connected with a pure block-tin worm or con- 
denser, answers very well to produce the common supply. 
But very critical operations require it to be again distilled in 
vessels of hard glass, chemically clean, which means much 
more than is commonly meant by " clean.^^ The solvent 
powers of pwre water are in some cases much greater than 
of common water. 

^ 407. The solvent powers of water far exceed those of any 
other known fluid. Nearly all saline bodies are, to a greater 
or less extent, dissolved by water, and heat generally aids 
this result. In case of common salt, however, and a few 
other bodies, cold water dissolves as much as hot. Gases 
are nearly all absorbed — that is, dissolved — in cold water, 
and some of them to a very great extent, while some, as 
hydrogen and common air, are very little taken up. They 
are all expelled again by boiling. Hot water dissolves many 
bodies which are quite insoluble in cold, especially when aided 
by small portions of alkaline matter. The waters of the hot 
springs in Iceland and in Arkansas deposit much silicious 
matter before solution ; and Dr. Turner found that common 
glass was dissolved in the chamber of a steam-boiler 
at 300°, and stalactites of silica were formed from the v/ire 
basket in which the glass was suspended. This is a subject 
of great importance in many geological speculations. 

^ 408. The powers of water as a chemical agent are very 
various and important. From its neutral, mild, and salutary 
character, we are accustomed to regard it only as a negative 
substance, possessed of little energy, while it is in fact one 
of the most important chemical reagents in our possession. 
Besides its solvent powers, we know that it combines with 
many substances forming a large class of hydrates ; hy- 
drate of lime and potash are examples. It is also, as 
we have seen, (^ 291,) essential to the acid properties of 
common sulphuric, phosphoric, and nitric acids, acting here 
the part of a much more energetic base than in the hydrates. 
It forms an essential part in the composition of many neutral 



§407. How are the solvent powers of water? Give examples. How 
does hot water act ia this respect ? Mention facts. § 408. What are the 
powers of water as a chemical agent ? How does it act in sulphuric acid, 
&/C. ? How in many salts ? 



248 NON-METALLIC ELEMENTS. 

salts, and can be replaced in composition by other neutral 
saline bodies ; while as water of crystallization it discharges 
still another important and distinct function, the crystalline 
forms of many salts being quite dependent on its presence 
in atomic proportions. 

§ 409. Peroxyd or Binoxyd of Hydrogen. — This curious 
compound was discovered in 1818 by M. Thenard. It is 
difficult of preparation by any process ; but that lately recom- 
mended by M. Pelouze is the best. It consists in decom- 
posing the peroxyd of barium by exactly as much very cold 
hydrofluoric acid, (fluosilicic or phosphoric acid may be 
used as well,) as will saturate the base, the whole being pre- 
cipitated as fluorid of barium. The reaction may be ex- 
pressed thus : 

Peroxyd of barium. Hydrofluoric acid. Fluorid of barium. Peroxyd of Hydrogen. 

BaO^+HF = BaF+HO^. 

The peroxyd of hydrogen remains dissolved in the sur- 
rounding water, which is freed from the insoluble fluorid of 
barium by filtration, and then evaporated under an air- 
pump by aid of the absorbing power of sulphuric acid. 

^410. Properties. — The properties of this body are very 
remarkable. When as free from water as possible, it 
is a syrupy liquid, colorless, almost inodorous, transparent, 
and possessed of a very nauseous, astringent, and disgusting 
taste. Its specific gravity is 1*453, and no degree of cold 
has ever reduced it to the solid form. Heat decomposes it with 
effervescence and the escape of oxygen gas. It can be 
preserved only at a temperature below 50°. The contact of 
carbon and many metallic oxyds decomposes it, often explo- 
sively, and with escape of light. No change is suffered by 
many bodies.which decompose it ; but several oxyds, as those 
of iron, tin, manganese, and others, pass to a higher state of 
oxydation. Oxyd of silver, and generally those oxyds 
which lose their oxygen at a high temperature, are reduced 
to a metallic state by this decomposition, which is quite an 
inexplicable fact. When diluted, and especially when acid- 
ulated, the peroxyd of hydrogen is more stable. This body 
dissolves with water in all proportions, bleaches litmus 



§ 409. What is the peroxyd of hydrogen ? By whom, and when dis- 
covered? How is it prepared? Explain the reaction. § 410. What are 
its properties? 



COMPOUNDS OF HYDROGEN. 249 

paper, and whitens the skin. None of its compounds aro 
known, nor does it seem to have any tendency to combine 
with other bodies. 

^411. Ozone. — There is a remarkable body given off 
during the electrolysis of vt'ater, having a peculiar odor, and 
very volatile. The sam.e odor is perceived when a series of 
electrical sparks is passed through a confined portion of 
air; and lastly, when phosphorus is slowly oxydized in a 
large volume of air, a peculiar odor is perceived, which is 
identical with the foregoing, and does not belong either to 
phosphorus or any of its compounds. This is the ozone 
of Prof. Schonbein, of which much has been said in the 
scientific journals for some time past. It bleaches power- 
fully, and converts many protoxyds (as those of calcium 
and barium) to peroxyds, and sulphurous to sulphuric acid. 
It is also decomposed by heat. All these are attributes of tho 
peroxyd of hydrogen ; and the latest opinion is, that these 
two curious bodies are identical in constitution, but differ in 
form.* 

4. Compounds of Hydrogen with other members of the 
Oxygen Group. 

§ 412. The eminently electro-positive character of hydrogen 
causes it to form well characterized and analogous compounds 
with all the members of the oxygen group. These binary 
compounds have frequently been called the hydracids, in 
distinction from those acid bodies already considered, which, 
in parity of language, have been called the oxacids. 

It is however more in accordance with facts and the prin- 
ciples of a philosophic classification, to look upon these bodies 
as having in reality the same essential characters as the 
chlorids, bromids, iodids, &c., of other highly electro-positive 
bases. We have already remarked, (§ 198, note,) that the 
principles of our nomenclature require all these bodies to be 
called after their electro-negative elements, i. e. chlorohydric, 



§ 411. What remarkable body is allied to binoxyd of hydrogen ? How 
is it produced? What are its properties? §412. What is said of tho 
compounds of hydrogen with the oxygen group? How are the hydracids 
now looked upon ? 

* American Journal of Science, vol. ii, (2d scries,) page 103. 



250 



NON-METALLIC ELEMENTS. 





Composition by weight. 


Symbol. 

HCl 


Hydrogen. 


Chlorine. 

35-41 


HBr 




Bromine. 

78-26 


HI 




Iodine. 

126-36 


HF 




Fluorine. 

18-70 


HS 




Sulphur. 

16-09 


HSe 




Selenium. 

39-57 



hromoliydric, &c. ; but common usage having established the 
other names, we shall not on the present occasion .depart 
from them. The compounds of hydrogen to be considered 
under this head are — 



Hydrochloric acid, 
Hydrobromic acid, 
Hydriodic acid. 
Hydrofluoric acid, 
Hydrosulphuric acid, 
Hydroselenic acid, 

§ 413. Action of Hydrogen with Chlorine, — These bodies 
have a very powerful affinity for each other, and combine 
under ordinary circumstances, when mixed in the gaseous 
state. Their affinity is such as to enable chlorine to decom- 
pose water (^ 263) and appropriate its hydrogen. In this 
way chlorine becomes one of the most powerful oxydizing 
agents known, since the nascent oxygen given off during 
the decomposition of water attacks any third body which 
may be present that is capable of combining with it. 

§ 414. The combination of hydrogen with chlorine depends 
on the action of light. We have already remarked that 
light, (§ 263,) and especially the violet ray, gives chlorine 
the power to decompose water. Chlorine prepared in the 
dark, and mingled with hydrogen, the mixture being also 
kept in the dark, will not combine with hydrogen nor de- 
compose water, and the two bodies seem altogether indifferent 
to each other. It has been long known that the direct rays 
of the sun would cause the explosive union of this mixture. 
But Dr. Draper has shown that chlorine gas which has been 
once exposed alone and dry to the sun's light, has acquired 
the power of forming this explosive union with hydrogen, 
even in the dark, and after the lapse of some time. The result 

Enumerate these, and give their formulas and constitution on the 
board. What is remarkable in this group? § 413. What of the affinity 
of chlorine and hydrogen ? How is it shown ? How does chlorine assist 
in oxydation? § 4J4. On what does the combination of hydrogen and 
chlorine depend ? Explain this as illustrated. 



COMPOUNDS OF HYDROGEN. 251 

of this union is of course hydrochloric acid. We see in thi^^ 
fact the best proof of the double state which chlorine can 
assume, (allotropism,) and which it enjoys in common with 
several other bodies. In its passive state, (as prepared 
in the dark,) it actually replaces hydrogen in the con- 
stitution of many organic bodies, or, in other words, assumes 
an electro-positive condition.* The effect of the sun's light 
is to confer a new state upon it, probably by a new arrange- 
ment of its molecules, (^ 217,) by which its character is 
completely changed. It then becomes highly electro-neg- 
ative. We have then in chlorine an instance of an element 
capable of acting in opposite characters under different 
circumstances. 

§ 415. Hydrochloric Acid, Chlorid of Hydrogen, Muriatic 
Acid, — This compound is formed from the action of dilute sul- 
phuric acid on common salt, or chlorid of sodium. The re- 
action may be thus described : 

NaCl-|-S03,HO=:r(NaO, S03) + C1H. 
No process is more simple. A little heat is required, and 
the gas being entirely absorbed by water, must be collected 
over mercury, or in dry vessels by displacement of air. 

§ 416. Properties. — Chlorid of hydrogen is a gas having 
a density of 1-269. It is nearly colorless, has the greatest 
avidity for water, and forms an acid fog by combining with 
the moisture of the air, which attacks the skin, has a most 
suffocating effect in respiration, and greatly iritates the eyes 
It is by no means, however, so unpleasant as chlorine. 
With a pressure of 26-30 atmospheres at 32°, it becomes 
a colorless liquid, which no degree of cold yet employed has 
solidified. The liquid acid of pressure dissolves bitumen, and 
attacked the cap-cement with which the tubes in Dr. Fara- 
day^s experiments were sealed. 

^417. This gas dissolves largely in cold water, forming 
an acid solution which is the common muriatic acid of com- 
merce, (or spirit of salt of the shops.) At common temper- 
atures water will absorb nearly 420 times its own bulk of 
muriatic acid gas. The solution is a powerful acid, of great 

How does chlorine appear to us under this view? §415. How is 
hydrochloric acid formed? What other names has it? §416. What is 
its condition ? What its properties? § 417. How much of this gas does 
water absorb ? 

* Mr. Graham calls the passive state of chlorine its ' zlncous' condition ; 
the opposite state he calls ' chiO)ous.^ 



252 



NON-METALLIC ELEMENTS. 



use in the arts and in the chemical laboratory. It may be 
prepared pure by an arrangement of apparatus like the figure. 
The common salt is contained in a large flask {a) which is 

fitted with a cork hav- 
ing two tubes, one of 
which [b) bends over 
and dips into the mid- 
dle bottle (c) which con- 
tains a little water to 
wash the gas. The 
last bottle {d) is filled 
with pure water, kept 
cool by ice or a free- 
zing mixture ; the gas, 
after beino^ washed in 




the middle 
passes by 



bottle, (c,) 
the second 
{e) to the 
where it 
Sulphuric 



scale in the second figure. 



bent tube 
last bottle, 
is absorbed. 

acid, equal in weight to 
the salt employed, is 
turned in successive 
portions upon the salt by 
the recurved funnel tube 
[f) shown on a larger 
This is called a safety t\ibe ; it is 
bent twice on itself, and has a ball blown on one of the 
turns. When a liquid is poured in at the funnel-top, it 
must rise as high as the turn, before it can pass down 
into the flask, and a portion of the fluid is therefore always 
left behind in the bend, which serves as a valve against 
the entrance of air, and also effectually prevents an 
explosion of the flask in case the tube of delivery 
should become stopped. It acts also as a safety tube 
against the danger of absorption, and the rushing back 
of the fluid in the bottles by atmospheric pressure, in 
case the gas in the flask should cease to be given out. 
This accident, which not unfrequently happens, is also 
provided for by the large open tube \g) in the middle 
bottle through which the bent tube descends into the 



What is the solution called? Explain the apparatus by which it is 
made. What is the action and use of the safet)^ tubes ? 



COMPOUNDS OF HYDROGEN. 253 

fluid, which is at the same time open to the air. This ar- 
rangement completely prevents the loss of the product in the 
last bottle, (<:/,) which, in case of a stoppage of the gas, 
would, by the partial vacuum resulting, be all driven back 
into the first bottle, and finally into the flask. 

The joints about the corks are made tight by a little yellow 
wax melted over them by a warm iron rod. Heat is applied 
by means of the furnace, (oj) or by a lamp. This same ap- 
paratus may be employed in making solutions of all the ab- 
sorbable gases, and is so simple as to be within the means 
of the humblest laboratory ; the essential parts being only 
wide-mouthed bottles, glass tubes, a gas bottle or flask, and a 
few corks.* 

§ 418. Pure hydrochloric acid is a colorless, highly acid, 
fuming liquid, having a specific gravity of 1 -2 when satura- 
ted, and it then contains 42 parts in a hundred of real acid. 
The purity of this acid is tested by its leaving no residue on 
evaporating a drop or two on clean platinum, and by its giving 
no milkiness when a solution of chlorid of barium is added 
to it, [sulphuric acid.] Neutralized by ammonia, it ought 
not to become black when hydrosulphuret of ammonium is 
added, [iron.] It may always be obtained pure, by diluting 
the acid of commerce until it has the specific gravity of 
1*11, and distilling. The product is colorless and pure, hav- 
ing the same density. The commercial acid is always im- 
pure, and colored yellow by free chlorine, iron, and organic 
matters. A solution of nitrate of silver detects the presence 
of a soluble chlorid, or of hydrochloric acid, by forming 
with it a white curdy precipitate of chlorid of silver, 
which is soluble in ammonia, but insoluble in acids or water. 
This acid is an electrolyte, (§ 231, 1,) and is also decomposed 
by ordinary electricity. A mixture of muriatic acid gas 
with oxygen, when electrified, results in the production of 
water and chlorine. 



§ 418. What are the characters of pure hydrochloric acid? How is it 
purified ? What impurities have the commercial acids ? How are they 
detected? 



* Corks are conveniently bored by a round iron rod tapered to a point, 
and fitted with a handle at one end. This is heated to redness, and will 
then make a smooth round hole of the required size. A round file serves 
to remove the charred portions and to fit it exactly to the tube. 

22 



254 NON-METALLIC ELEMENTS. 

^419. The uses of hydrochloric acid are very numerous. 
Its decomposition by oxyd of manganese affords the easiest 
mode of procuring chlorine. It dissolves a great number of 
metals forming chlorids, from which these metals may be ob- 
tained in their lowest state of oxydation. In chemical analy- 
sis and the daily operations of the laboratory it is of in- 
dispensable use. Mingled with half its own volume of 
strong nitric acid, it makes the deeply colored, fuming and 
corrosive aqua regia. This mixed acid evolves much free 
chlorine, which in its nascent state has power to dissolve 
gold, platinum, &c., forming chlorids of those metals, and 
not nitromuriates, as was formerly supposed. As soon as all 
the chlorine is evolved, this peculiar power of the aqua 
regia is lost. 

^ 420. Hydrochloric acid is made in the arts in immense 
quantities, especially in England, where the carbonate 
of soda is largely made from common salt, (chlorid of so- 
dium,) by the action of sulphuric acid. The vast volumes 
of chlorid of hydrogen which are evolved in. this process, 
are by law required to be condensed, to avoid the injury to 
vegetation and health formerly experienced, from being al- 
lowed to escape into the atmosphere. In this way, pure 
hydrochloric acid is made as an incident to other processes, 
in such quantities as to overstock the market. 

§ 42 1 . Hydrohromic Acid — Bromid of Hydrogen, — Hydro- 
gen and bromine do not act upon each other in the gaseous 
state, even by the aid of the sun's light ; but a red heat or 
the electric spark causes union, only among those particles, 
however, which are in immediate contact with the heat, 
the action not being general. Hydrobromic acid may be 
prepared by the reaction of moist phosphorus on bromine 
in a glass tube. The gas given oiF must be collected over 
mercury. It is composed like hydrochloric acid, of equal 
volumes of its elements not condensed. Its specific gravity 
is 2-731, and it is condensed by cold andjpressure into a liquid. 
In its sensible properties it bears a close resemblance to hy- 
drochloric acid. With the nitrates of silver, lead, and mer- 
cury, it gives white precipitates similar to the chlorids, while 



§ 419. What are its uses ? What is aqua regia 7 What use has it, 
and on what dependent? § 420. What is said of the abundance of this 
acid? §421. How do hydrogen and bromine act together? How is 
hydrobromic acid prepared ? What character lias it ? 



COIVl^OUNDS OF HYDROGEN. 255 

the iodids of these metals are very highly colored. It has a 
strong avidity for water, and dissolves largely in it, giving 
out much heat during the absorption. The saturated aque- 
ous solution has the same reactions as the dry acid, and 
fumes with a white cloud in contact with air. It dissolves 
a large quantity of free bromine, acquiring thereby a red 
tint. 

^ 422. Hydriodic Acid — lodid of Hydrogen,— Thi^ body 
may be formed by the direct union of its elements at a red 
heat, but is more easily prepared by acting on iodine and 
water with phosphorus, by which means the gas is given 
out in large quantities. The action of phosphorus and 
iodine is violent and dangerous, but may be regulated and 
made safe by putting a little powdered glass between each 
layer of phosphorus and iodine. The glass serves only to 
moderate and regulate the action of the elements. Phos- 
phoric acid is formed and remains 
in solution, while the hydriodic 
acid gas is given out, and may be 
collected over mercury, or dissolv- 
ed in water. The dry gas has 
a great avidity for water. Its spe- 
cific gravity is 4*385 air = 1 ; being 
formed like the two last of one 
volume of each element uncon- 
densed. Cold and pressure reduce it to a clear liquid, 
which freezes into a colorless solid at — 60° Fahr., having 
fissures running through it like ice. It forms a very acid 
fluid by solution in water, which has, when saturated, a spe- 
cific gravity of 1-7, and emits white fumes. 

The aqueous solution is also prepared by transmitting a 
current of hydrosulphuric acid through water in which free 
iodine is suspended. The gas is decomposed, sulphur set 
free, and hydriodic acid produced, which is purified from 
free hydrosulphuric acid by boiling, and from sulphur by fil- 
tration. 

^ 423. The aqueous hydriodic acid is easily decomposed 
by exposure to the air, iodine being set free. It forms char- 
acteristic, highly colored precipitates with most of the met- 



§ 422. How is hj^driodic acid prepared ? What is the reaction ? WJiat 
are the properties of the gas? How else may the aqueous sohitiou be 
prepared? §423. What properties has the aqueous hydriodic acid? 




256 NON-METALLIC ELEMENTS. 

als, particularly with lead, silver, and mercury. Bromine 
decomposes it, and chlorine decomposes both hydriodic and 
hydrobromic acids, thus establishing the proper relations of 
these bodies. This acid is a valuable reagent ; and its pres- 
ence in solution is easily detected by a cold solution of 
starch with a few drops of strong nitric or sulphuric acid, 
which instantly gives the fine characteristic blue of the 
iodid of starch. 

^ 424, Hydrofluoric acid, orfluorid of hydrogen, is a com- 
pound which results from the decomposition of fluor-spar 
by strong sulphuric acid. The operation must be performed 
in a retort of pure lead, silver, or platinum, and requires a 
gentle heat. The fiuorine quits the lime and joins the hy- 
drogen of an atom of water in the acid, forming hydrofluoric 
acid, while sulphate of lime remains behind ; or, expressed 
in symbols, 

Fluorid of Sul. acid. Sul. lime. Fluorid of 

calcium. hydrogen. 

CaF + SO3, HO =2 SO3, CaO + HF. 
The fluor-spar must be pure, and especially free from silica. 

^ 425. Properties. — Thus procured, hydrofluoric acid is 
a gas which at 32^ is condensed into a colorless fluid, with a 
density of 1*069, and which can be preserved as a fluid 
even at higher temperatures in well stopped bottles of silver 
or lead. Its avidity for water is extreme, and when brought 
in contact wdth it, it hisses like a red-hot iron. Its 
aqueous solution, as well as the vapor of the acid, attacks 
glass very powerfully, and is often used to etch it, as, 
for example, in marking the test bottles in the laboratory, or 
biting in designs traced in wax on the surface of glass plates. 
It is a powerful acid with a very sour taste, neutralizes alka- 
lies, and permanently reddens blue litmus. On some of the 
metals its action is very powerful ; as, for example, it unites 
explosively with potassium — heat and light being evolved. 
It attacks and dissolves, wath the evolution of hydrogen, 
certain bodies which no other acid can affect, such as sili- 
con, zirconium, and columbium. 



What are the mutual relations of iodine, bromine, and chlorine, as 
shown by their compounds with hydrogen ? How is the presence of hy- 
driodic acid detected ? § 424. What is hydrofluoric acid ? Explain the 
reaction by which it is produced. § 425. What are the properties of this 
body ? What is its most remarkable affinity? What are its relations to 
the metals ? 



COMPOUNDS OF HYDROGEN. 257 

Silicic, titanic, coliimbic, and molybdic acids are also dis- 
solved by it, although no other acid affects them. 

^ 426. Hydrofluoric acid is a most dangerous body to deal 
with. It attacks all forms of animal matter with wonderful 
energy. The smallest drop of the concentrated acid pro- 
duced ulceration and death, when applied to the tongue of 
a dog. Its vapor floating in the air is very corrosive, and 
should be carefully avoided. If it falls, even in small spray, 
on the skin of the hand or any part of the body, it pro- 
duces a malignant ulcer, which it is very difficult to cure. 
Any considerable quantity of it would prove fatal. For 
this reason it is quite inexpedient for unexperienced per- 
sons to attempt its preparation. By using a weaker sulphuric 
acid, however, and having water in the condenser, no risk is 
incurred. As before remarked, it attacks silica more pow- 
erfully than any other body, and their mutual affinity is one 
of the most powerful known to us. This fact puts us in 
possession of an admirable mode of analyzing silicious 
minerals, when we do not wish to fuse them with an 
alkali. By exposing the fine powder of the moistened min- 
eral to the vapor of the hydrofluoric acid, all the silica is 
taken up and carried away as hydrofluosilicic acid gas, 
(§ 363.) 

§ 427. The hydrofluoric acid was formerly called fluoric 
acid, and the fluor spar, a fluate of lime. We now know 
that this mineral is a fluorid of calcium, in exact analogy 
with the chlorid of sodium, and a very numerous class of 
similar binary compoi^ds, with which our study of the met- 
als will familiarize us. 

^ 428. HydrQ sulphuric Acid — Sulphureted Hydrogen, — 
When the protosulphuret of iron or of antimony is treated 
with a dilute acid, eflervescence occurs, and a gas is given 
out having a most disgusting fetid odor, which at once re- 
minds us of the nauseous smell of bad eggs. This is sul- 
phureted hydrogen gas, one of the most useful reagents to 
the chemist, especially in relation to the metallic bodies. 

§ 429. Properties. — This gas is colorless, and less offen- 



What acids are dissolved by it ? § 426. How does it affect animal mat- 
ter ? What caution is given ? What analytic use is named for this acid ? 
§ 427. What was this acid formerly called ? What more exact knowl- 
edge do we now possess? §428. What is hydrosulphuric acid, and how 
set free ? What other name has it ? § 429. What are its properties ? 

22* 



258 NON-METALLIC ELEMENTS* 

sive in quantity than when the air is contaminated with only 
a trace. It burns with a pale blue flame like that of sul- 
phur, water and sulphurous acids being the products. If oxy- 
gen is mingled with it, and the mixture ignited, or touched 
with a match, it explodes with a shrill sound, sulphur being 
deposited. When the oxygen is in the proportion of 150 meas- 
ures to 100 of sulphureted hydrogen, the combustion is com- 
plete, and only sulphurous acid and water are formed. Strong 
nitric acid and chlorine gas also decompose it, and sulphur 
is deposited. It has a specific gravity of 1*171, and 100 
cubic inches of it weigh 36*33 grains. At a temperature of 
50°, it is made liquid by a pressure of 14*5 atmospheres, 
and at 122° Fahr. it freezes into a white confused crystal- 
line solid, not transparent, and which is much heavier than 
the fluid, sinking in it readily. 

§ 430. Cold water dissolves its own volume of sulphu- 
reted hydrogen, and acquires its peculiar odor and properties. 
When recently prepared, it takes the place of the gas as a 
test ; but it is so easily decomposed by contact with the air, 
with the deposition of sulphur, that it cannot long be kept 
on hand. 

The student should always have at hand in the laboratory 
a little gas bottle, like the figure, holding 
some fragments of protosulphuret of iron, 
to which, when the gas is wanted, a little 
water is added, and then a few drops of 
oil of vitriol, abundant eflervescence 
comes on, and the g§s is delivered by the 
bent tube into any solution which we de- 
sire to treat with it. 
§ 431. Properties and Uses, — This gas possesses the prop- 
erties of an acid, its aqueous solution reddens litmus paper, and 
it forms compounds with many bases. It precipitates from 
solution all the metals whose sulphurets are insoluble in 
water, often giving the most characteristic precipitates. It 
thus enables the chemist to effect many separations of met- 



How does it smell? Is it combustible ? How does it burn when min- 
gled with oxygen ? Is it condensable to a fluid ? § 430. How much of 
it will water dissolve ? What properties has the solution ? What objec- 
tion to its use ? What mode is preferred for using this reagent? § 431. 
How is it seen to be an acid? What are its properties and uses? How 
does it act with the metals ? How is its presence detected ? 




COMPOUNDS OF HYDROGEN. 



259 




als with ease and certainty, and, as before remarked, is one 
of his most valuable reagents. Its presence in solution is 
at once detected by its blackening the salts of lead. Char- 
acters drawn on paper with a solution of the acetate of lead, 
are quite colorless ; but a stream of 
sulphureted hydrogen at once causes 
them to stand forth in deep black, 
its action producing the dark sul- 
phuret of lead. The fanciful draw- 
ing annexed is usually shown by Dr. 
Hare to his class ; and is called by 
him a sympathetic picture. The 
characters, before almost invisible, 
appear as if by magic, as the gas- 
pipe is waved before them. The 
paper should be damp, or the reaction does not readily take 
place. 

^ 432. It occurs in many mineral springs in solution, giv- 
ing the water highly valuable curative characters. Such 
springs are much resorted to in this country, as at Avon, N. 
Y., and the sulphur springs of Virginia. The disgust at 
first felt at drinking these nauseous waters is soon over- 
come, and those patients who take them in large quantity 
soon observe the gas to penetrate their whole system and 
exude in their perspiration. Silver coin, and other silver 
articles in the' pockets of such persons are soon completely 
blackened by the coating of sulphuret of silver formed on 
their surface. 

§ 433. Although salutary when used in the stomach, it 
has been found to be a deadly poison to the more delicate 
animals, even when present in the air in only a small quan- 
tity. The operative chemist is, however, constantly in the 
habit of breathing it with impunity, for the atmosphere of an 
active laboratory is almost never free from it. 

§ 434. When sulphurous acid and sulphureted hydrogen 
gas are brought together in a common receiving vessel, mu- 
tual decomposition ensues, and the sulphur of both is 



What is the sympathetic picture ? § 432. How does this gas occur in 
nature ? What use is made of sulphureted waters ? § 433. What is said 
of the effect of this gas on the system of animals ? \ 434. What is the 
reaction when sulphuric acid and hydrosulphuric acid gases are mingled ? 



260 



NON-METALLIC ELEMENTS. 



thrown down in a yellow cloud, which closely attaches itself 
to the sides of the vessel. The same arrangement of ap- 
paratus which was em- 
ployed for illustrating the 
formation of sulphuric 
acid, will answer in this 
experiment, substituting 
the materials for sulphu- 
reted hydrogen in the 
flask, {^.) This decompo- 
sition is supposed some- 
times to occur in volcan- 
ic districts. 

§ 435. Hydi'oselenic Acid — Seleniureted Hydrogen, — This 
body is exactly analogous to the foregoing, and is formed in 
the same manner by decomposing the protoseleniuret of 
any of the more easily oxydized metals, with a weak acid. 
Its properties and reactions are very similar to those of the 
hydrosulphuric acid. It is absorbed by water, turns the 
skin brown, and irritates the mucous membrane. 




5. Compounds of Hydrogen with Class 2, or the Nitrogen 
Group. 

§ 436. The compounds which hydrogen forms with the 
nitrogen group, are strongly contrasted in chemical and 
physical characters with the remarkable natural family 
which has just engaged our attention. The latter are all 
acid, and generally in an eminent degree. The compounds 
of hydrogen with the nitrogen group are, on the contrary, 
either neutral or strongly basic, forming a series of salts 
or peculiar compounds with the hydracids before named ; 
thus furnishing a strong reason for the propriety of the 
arrangement which we have adopted in our classification. 



§ 435. What is hydroselenic acid, and how allied to the last body ? 
§ 436. What is said of the compounds of the hydrogen with the nitrogen 
group ? What compounds are named ? Give their symbols and compo- 
sition. 



Symbol. 

NH„ 


Nitrogen. 

14-06 


— \ 

Hydrogen. 

3 


NH, 


14-06 


4 


NH. 


14-06 


2 


,PH, 


PhosphoruSc 

31-38 


3 



COMPOUNDS OF HYDROGEN. 261 

The compounds named under this head, are — 

Composition by weight. 
Symbol. 

Ammonia, 

Ammonium, 

Amidogen, 

Phosphureted hydrogen, PHg 

^ 437, Ammonia^ and the other compounds of nitrogen 
and hydrogen, might with propriety be treated under or- 
ganic chemistry, since hydrogen and nitrogen do not, by any 
direct means, unite as gases, and all the compounds of 
ammonia may uhimately be traced back to an organic origin. 
Ammonia is almost invariably one of the products of the 
decomposition of those organic matters which contain nitro- 
gen ; and we shall see, when we come to study these bodies, 
that their elements are so arranged, that we might expect 
such a result. Ammonia is however so important a body 
in relation to the metals, and, in fact, as a reagent in nearly 
all chemical experiments, that we shall find it more conven- 
ient to make an acquaintance with it here, than at a later 
period of our studies. 

§ 438. History. — " Sal ammoniac'^ and the watery solution 
of ammonia have been long known, and probably were 
in use among- the ancients. The very name ammonia indi- 
cates antiquity.* The sal-ammoniac, sulphate of ammonia, 
and ammonia-alum are found among the products of volca- 
noes. Free ammonia is exhaled from the foliage and 
found in the juiges of certain plants, in the perspiration of 
animals, in iron rust and absorbent earths. Rain water also 
contains a small quantity of ammoniacal salts, washed out of 
the atmosphere : and the guano so much valued as a manure, 
abounds in various ammoniacal salts. 

§ 439. Preparation. — Ammonia is best prepared for us6 
by decomposing one of its saline compounds, as the carbonate 
(sal volatile) or sal-ammoniac, by an alkali and heat. For 

§437. Where might ammonia be more properly treated of ? §438. 
What is known of the antiquity of ammonia? What ammoniacal com- 
pounds are found native? What other natural sources of ammonia are 
named? §439. How is ammonia prepared ? 

* From animon, an epithet by which Jove was known, and ammos^ 
Band, in allusion to tlie Egyptian desert of Amnion, where sal ammoma 
was first obtained. 



262 NON-METALLIC ELEMENTS. 

this purpose equal parts of dry powdered sal-ammoniac 
and freshly slaked dry lime are well mingled and heated, 
either in a glass vessel, or if the quantity is considerable, in 
an iron vessel. The caustic lime takes the chlorine, forming 
a chlorid of calcium, and ammonia is given out as a gas. 

§ 440. Properties. — The dry gas is colorless, having the 
very pungent smell so well known as ''hartshorn,' It is, when 
undiluted, quite irrespirable, and attacks the eyes, mouth, and 
nose powerfully. It is alkaline, and has therefore been 
called the volatile alkali. Being very rapidly absorbed by 
water, it must be collected over mercury or in inverted dry 
vessels. It does not support the combustion of a candle, and 
does not burn itself, although a small jet of the gas will 
burn in pure oxygen, and the flame of the candle, as it goes 
out, is slightly enlarged with a yellowish fringe. Mixed 
with an equal volume of oxygen, it explodes with the 
electric spark, forming water and free nitrogen. The dry 
gas passed through a red-hot tube is completely decomposed ; 
200 measures of the gas yielding 400 measures after de- 
composition, which by analysis has been found to be formed 
of 300 measures of hydrogen and 100 of nitrogen. The 
specific gravity of dry ammonia is therefore (§ 191) 
0*5898, and 100 cubic inches must weigh 18-28 grains. By 
pressure it is easily converted into a liquid, which freezes at 
— 103° Fahrenheit, producing a white translucent crystalline 
solid, which is heavier than the liquid. 

§ 441. The solution of this gas in wafer (called " aqua 
ammonicB,^^ and sometimes improperly liquid ammonia) is 
easily prepared, and possesses all the peculiar properties of 
the gas. This is best made by an arrangement like the an- 
nexed figure, called "Woulfe's apparatus." This consists 
essentially of the gas bottle, (a,) which contains the materials 
to generate the gas, and is placed over a furnace. Three 
three-necked bottles [b c d) are all connected with a by a 
series of bent tubes, ( i i i i.) The gas, in passing from a by i, 
must go through a portion of water in 5, where it is absorbed. 
It is prevented from escaping by a tube in the middle orifice, 



§440. What are the properties of this gas? How does it affect com- 
bustion ? How is it analyzed ? What is its constitution by weight and 
volume? What is its density ? How does cold affect it ? §441. How 
is aqua ammoniae prepared ? Explain the Woulfe*s apparatus and its mode 
of action. 



COMPOUNDS OF HYDROGEN. 



263 



(o,) which has its lower end dipping a little way into the 
water of each bottle. The effect of this is to cause a column 
of liquid to play up and down in o, as the pressure of the 
gas varies. Each tube {i) has a shorter end not reaching the 
fluid. Things being thus arranged, and the tightness of all 
the joints and corks being secured by yellow wax, the gas 
bubbles through b, until the water can absorb no more ; it 
then passes on to c, and then to d, saturating each in turn. 




In the last vessel is a little mercury under which the bent tube 
(?') dips, with the design of creating a slight pressure on the 
whole apparatus, as is indicated by the height of the column of 
water in o o o. It only remains to keep the whole {b c d) 
cold, and the water in the bottles will then soon become sat- 
urated with the gas. The first bottle is usually contami- 
nated by foreign matters, and is rejected. Under the sul- 
phuret of ammonium will be found a more simple form of the 
same apparatus formed of common wide-mouthed bottles. 

^ 442. The saturated aqueous solution of ammonia has a 
specific gravity of about 0875, is colorless and transparent, 
and exhales the gas abundantly ; of this density it contains 
32 per cent, of real ammonia. It must be kept in tight 
bottles, to prevent the loss of strength and the absorption of 
carbonic acid gas from the air. It has all the characters of 
an alkali, it saturates the most powerful acids, and forms a 
series of salts which are all soluble in water and are all vola- 
tilized at a red heat. It boils vehemently at 130^, and 
freezes at about 40° below zero. It browns yellow turmeric 
paper temporarily, the original color returning as the gas 
evaporates. 

What properties ? § 442. What gravity has the saturated aqueous so- 
lution ? What characterizes its salts ? 



264 NON-METALLIC ELEMENTS. 

^ 443. The presence of ammonia is always recognizable 
by its odor, by its action on turmeric or blue cabbage paper, 
(which last it turns green,) and especially by the white cloud 
of muriate of ammonia which fills the air on bringing a rod 
moistened with hydrochloric acid within its influence. 

§ 444. Ammonium^ (NH^.) — This compound of hydrogen 
and nitrogen has never been isolated, though we have every 
reason to believe in its existence. When a solution of ammo- 
nia, or of sal-amracniac, is electrolized, nitrogen escapes at 
the + side and hydrogen at the — side ; but if the latter pole 
is made by using a portion of mercury, no hydrogen is 
evolved, but the mercury swells up, loses its fluidity, be- 
comes like soft butter, and gradually attains many times 
its original bulk, having the lustre and general character of 
an amalgam. This spungy mass, as soon as the electric 
action ceases, rapidly suflers decomposition. Ammonia and 
hydrogen are set free in the proportion of 1 to 2, and the 
mercury regains its original state unaltered. Berzelius and 
other able chemists explain this reaction, on the ground that 
the ammonia, by gaining an additional equivalent of hydro- 
gen, assumes the peculiar character of a metal, and unites 
with mercury, forming an amalgam. This hypothetical 
metal can replace potassium and sodium perfectly in com- 
bination, and is therefore isomorphous with them. All the 
salts of ammonia are, on this view, derived from this radical, 
and its union with the oxygen group gives us a series of 
bodies analogous to the chlorids, bromids, &;c., of the other 
electro-positive bases. 

§ 445. Amidogen, (NH^O — This is another compound of 
hydrogen and nitrogen v^d:iich has never been isolated, and 
which, according to the views of several distinguished chem- 
ists, is the radical of all the ammoniacal compounds. By 
this view, common ammonia is looked upon as a compound of 
amidogen and hydrogen, or NH^-I-H, and ammonium as 
amidogen + 2H or NH^+H^. But this subject belongs 
properly to the organic chemistry, and will be again taken 
up there. 



§ 443. How is ammonia recognized ? § 444. What is ammonium ? 
How is some proof of its existence found ? What properties does it con- 
fer on mercury ? What view has this given origin to ? On this view 
what are ammoniacal compounds? §445. What is amidogen? Give 
the constitution of ammonia and ammonium on this view. 



COMPOUNDS OF HYDROGEN. 



265 



^ 446. Hydrogen and Phosphorus — Phosphureted Hy^ 
drogen. — This gaseous body is formed when the phosphuret 
of calcium or some other alkaline metal, is thrown into 
water ; but is more conv^eniently prepared by employing 
quick-lime lately slaked, water, and a {q\y sticks of phospho- 
rus, in a small retort, the ball of which is nearly filled with the 
mixture. A gentle heat generates the gas, which breaks 




from the surface of the water (beneath which the beak of the 
retort dips very slightly) in bubbles, which inflame spontane- 
ously as they reach the air, rising in beautiful wreaths of 
smoke, which float in concentric, expanding rings. This 
gas loses its spontaneous inflammability by standing a 
time over water, a body not yet obtained in a separate 
form being deposited. A few drops of ether or oil of tur- 
pentine destroy this spontaneous inflammability ; and on the 
other hand, a very little nitrous acid restores this property 
to the gas which has lost it. 

^ 447. Properties. — This gas has a disgusting, heavy 
odor like putrid fish, which is far more annoying than sul- 
phureted hydrogen. It is transparent and colorless, has a 
bitter taste, and if dry, may be kept unchanged either in the 
light or dark. It is deadly when breathed. When pro- 
cured as just described, it acts very violently with oxy- 
gen gas. If bubbles of it are allowed to enter a jar of 
oxygen, each bubble burns with a most brilliant light and 
a sharp explosion. The mixture of even a very small quan- 
tity with oxygen would be quite hazardous. 

^ 448. Phosphureted Hydrogen is neither alkaline nor 
acid, but it has more resemblance to an alkali than to an acid, 



§446 What is phosphureted hydrogen, and how prepared? What 
remarkable property has the fresh gas? Is this property constant? § 447. 
What are its characters ? How does it react with oxvgen ? 

23 



266 NON-METALLIC ELEMENTS. 

since it forms, with several metallic chlorids, compounds 
analogous to those which ammonia forms with the same 
bases. It also combines with hydrobromic and hydriodic 
acids, forming colorless crystalline salts, which are decora- 
posed by water. 

§ 449. Three pJiosphurets of hydrogen have been distin- 
guished, which have the formulas PH, PH^, and PH3. 
The last is the pure gas, the second is the spontaneously 
inflammable body, and the first is a solid. 

5. Compounds of Hydrogen with the Carbon Group, 

^ 450. Carbon and Hydrogen unite to form a vast number 
of compounds, all of which, directly or indirectly, are the 
product of organic life, and will therefore (with two excep- 
tions) be discussed more properly in the organic chemistry. 
Many of these compound bodies act like elements, forming 
with other bodies compounds having the binary character, 
and even neutralizing powerful acids, although not themselves 
possessed of alkaline characters. From this cause they 
have been called compound radicals^ as an element may, in 
like manner, be called a simple radical. 

§ 451. The carbo-hydrogens, as these bodies are often 
called, are sometimes solids at common temperatures, as 
parafEne and naphthaline ; or liquids, as the oils of turpen- 
tine, lemons, and naphtha. Two of them are gases, and being 
also products of the mineral kingdom, they may be properly 
discussed under inorganic chemistry. We refer to the 

Composition by weight. 

, ^ , 

Symbol. Carbon. Hydrogen. 

Light Carbureted Hydrogen gas, CH^ 6 2 

defiant or heavy carbureted 

hydrogen gas, C2H2 12 2 

§ 452. Light carbureted hydrogen gas; marsh gas ; fire 
damp; or di-carburet of hydrogen. — This gas occurs abund- 
antly in nature, being formed nearly pure by the decomposi- 

§ 448. Is this gas alkaline or acid ? What compounds analogous to 
salts does it form? § 449. How many and what phosphurets of hydro- 
gen are known ? § 450. What is said of the number and nature of the 
compounds of carbon and hydrogen ? Of what are they the product ? 
How do they act in combination? What are they therefore called? 
§451. How do the carbo-hydrogens present themselves? What two 
are referred to? Give their formulas and composition. 



COMPOUNDS OF HYDROGEN. 267 

ti'on of vegetable matter under water. The bubbles which 
rise, when the leaves and mud of a stagnant pool or lake are 
stirred, are the light carbureted hydrogen, with about -^\ of 
carbonic acid. It is also evolved in large quantity in coal 
mines, but is then accompanied by several other gases. In 
the salt regions of this country it is given out abundantly 
with olefiant gas from some of the artesian wells bored for 
salt water. It i-s also sometimes blown out in a strong blast 
from fissures in iho earth ; aind it forms a part of the gas 
employed to light cities. 

^ 453. Preparation, — This gas may be prepared artificially 
by a process lately discovered by M. Dumas, which is by 
mixing equal parts of acetate of soda, and solid hydrate of 
potash, with one and a half parts of quicklime. The mix- 
ture is strongly heated in a retort, when the gas, perfectly 
pure, is disengaged abundantly, and may be collected over 
water. The hydrate of potash decomposes the acetic acid 
at a high heat, and takes from it tw^o equivalents of carbonic 
acid, while two equivalents of marsh gas are given off; 
thus : 

Acetic acid, C^Hg O3 ^ __ C Carbonic acid, 2 Eq Cg O^ 
Water, H O S — "^ Marsh gas, 2 Eq C^ H^ 



C, H, O, C, H, O, 

The use of the lime is to keep the potash from acting on the 
glass. 

§ 454. Properties -—This gas has a density of -5595, and 
100 cubic inches of it weigh 17-41 grains. It is composed 
of one volume of carbon and two volumes of hydrogen, or 
six parts by weight of the former to two of the latter. It is 
neutral, inodorous, tasteless, and respirable without poison- 
ous effects. Water absorbs very little of it, and it has not 
been condensed into a liquid. Twice its bulk of oxygen 
burns it completely, with a loud explosion, forming water 
and an equal volume of carbonic acid. In the air it burns 
quietly with a bright yellow flame, giving the same products. 
It is not easily decomposed ; but at a red heat, in a porce- 



§ 4.52. What other names has the h's^ht carbureted hydrogen .? WJiat 
natural supplies have we of it? § 453. How is it prepared? Give the 
reaction. § 454. What is the density and composition of this gas ? Give 
its general properties. How does it act with chlorine ? 



268 NON-METALLIC ELEMENTS. 

lain tube, it deposits carbon and gives out hydrogen. With 
moist chlorine in the sun-light, it forms carbonic and hy- 
drochloric acids, but is not affected by it in the dark. 

^ 455. Olejiant Gas, or heavy Curhureted Hydrogen Gas. 
— This gas was discovered in 1796, by certain associated 
Dutch chemists, who gave it the name of olefiant, because 
it forms a peculiar oil-like body with chlorine. It is pre- 
pared by mixing strong alcohol with five or six times its 
weight of oil of vitriol in a capacious retort, and applying 
heat to the mixture. The action is complicated and cannot 
be w^ell explained at this time. Ether distils over soon 
after the heat is applied, and with it, the olefiant gas which 
may be collected over water. The alcohol becomes car- 
bonized, froths up very much, and carbonic and sulphurous 
acids are given ofT towards the close of the process. The 
gas can be purified by passing it first through a wash-bottle 
containing a solution of potash, and then through oil of vitriol ; 
the potash removes the acid vapors, and the oil of vitriol re- 
tains the ether. 

^ 456. Properties, — Olefiant" gas is a neutral, colorless, 
tasteless gas, nearly free from odor, and having a density of 
0-981, 100 cubic inches of it Vv^eighing 30-57 grains. It 
burns with a most brilliant white light, and evolves much free 
carbon. Its splendid combustion makes it a favorite sub- 
ject of experiment. With an equivalent quantity of oxy- 
gen gas, it explodes with a tremendous detonation, which is 
too severe even for very strong glass vessels. Bubbles of 
the mixture may be exploded by a burning paper, as they 
rise from beneath the surface of water. It is decomposed 
by passing through tubes heated to redness, and much car- 
bon is deposited. This effect happens in the iron re- 
torts of city gas works, in which crusts of pure carbon, some- 
times of great thickness, accumulate from the decomposition 
of the gas. 

^ 457. As already remarked, this gas forms a remarka- 
ble compound with chlorine ; the gases unite (2 volumes of 
chlorine and 1 of olefiant) by simple contact, the dense oily 



§ 455. When, and by whoni, was olefiant gas discovered? Whence 
its name? How is it prepared? What is the result? §456. What 
properties has olefiant gas ? How does it burn ? How does it act with 
oxygen ? How is it decomposed? What happens in large gas retorts? 
§ 457. How does olefiant gas act with chlorine ? 



COMrOUNDS OF HYDROGEN. 269 

liquid collects on the sides of the air-jar and surface of the 
water, and may be received as it fails in a basin placed for 
the purpose under the jar. 

If two measures of chlorine and one of olefiant gas be 
fired as soon as the mixture is made, by a candle, or lighted 
match, from the open mouth of the jar, the hydrogen of the 
olefiant unites with the chlorine, and all the carbon of the 
former is set free in a dark cloud, filling the vessel. 

^ 458. Coal gas and resin gas are much used for illumi- 
nating cities ; they are formed chiefly of light carbureted hy- 
drogen and olefiant gas, with some other volatile hydrocar- 
bons. Their illuminating power is in proportion to the 
amount of olefiant gas contained in the mixture. Numerous 
products from the destructive distillation of coal and resin 
require to be removed before the gas is fit for use. It is 
accordingly washed in milk of lime to free it from sulphu- 
reted hydrogen and carbonic acid, and sometimes with di- 
lute sulphuric acid to remove ammonia. Tar and soluble 
oils are condensed by passing the gas through a series of 
iron pipes in water, which is done before it goes to the lime 
purifiers. The gas from oil has a higher illuminating power, 
and needs no purification when well prepared. 

A natural supply of coal gas, composed of light carbureted 
hydrogen and olefiant gas, is used to illuminate the village 
of Fredonia, N. Y. ; and some of the salt works in Ken- 
awha, Ya., are heated by the burning gas conducted for the 
purpose under the kettles. Yast volumes of this gas are 
given off from the Artesian borings in those regions. 

^ 459. Hydrogen combines with boron, forming a combus- 
tible gas, which burns with the green flame peculiar to the 
compounds of boron, and deposits boracic acid. Its compo- 
sition and properties are not well known, but from analogy 
we may suspect the existence of an extensive series of bo- 
rurets of hydrogen, and possibly siliciurets of the same 
element. 



If the mixture is at once fired, how does it act ? § 458. For what are 
coal and resin gases used? On what depends their illuminating power? 
How are they purified? What natural supplies of coal gas are named i^ 
§459. What compound of hydrogen and boron is named ? 

23* 



270 METALLIC ELEMENTS. 

6. Combustion and the Structure of Flame, 

§ 460. Combustion is the disengagement of light and heat, 
which accompanies chemical combination. Nearly all our 
operations being performed in presence of the oxygen of the 
atmosphere, the term combustion has come to be restricted, 
in a popular sense, to the union of bodies with oxygen, 
when heat and light are accompaniments of such union. 

Combustible bodies, in the common sense of the term, are 
those which burn (i.e., unite with oxygen with heat and light) 
under ordinary circumstances. Thus, carbon, sulphur, and 
phosphorus, are among the elementary combustibles ; and tar, 
oils, wood, &c., are compound combustibles. Oxygen being 
possessed of stronger affinities than any other elementary 
body, forms compounds with those bodies which are burned 
in it, which are no longer combustible ; thus iron which 
has been burnt (i. e. oxydized) in oxygen gas, (§ 254,) is no 
longer capable of a similar change, because we have no 
other body, which, at common temperatures, can remove the 
oxygen from combination. Iron will also burn brilliantly in 
sulphur vapor, forming a compound, (protosulphuret of iron,) 
which is incombustible in an atmosphere of sulphur vapor, 
but which will still burn in oxygen gas. This is only say- 
ing that the affinities (i. e. the electro negative qualities) 
of oxygen are more powerful than those of sulphur. 

^ 461. The division of elementary bodies into coinbustibles 
and supporters of combustion, was proposed by Dr. Thom- 
son, and that classification has prevailed with English and 
American authors to a great extent. This principle is radi- 
cally defective as a guide to any philosophical arrangement 
of bodies, since it seizes on a single phenomenon accompa- 
nying chemical union, and disregards most of those natural 
analogies which group the elements into distinct classes. 

It has been remarked by an old writer on chemistry, that 
" combustion is the grand phenomenon of chemistry." It 
would be more conformable to truth to say, that affinity is 
the grand phenomenon of chemistry, and that its exertion is 
sometimes accompanied by the evolution of heat and light. 

§460. What is combustion? What popular restriction has arisen in 
the use of this term? What is commonly meant by combustible bodies? 
What is said of bodies which have been burnt in oxygen? Illustrate 
this. § 461. What is said of the division of bodies into combustibles and 
supporters of combustion ? 



COMBUSTION AND FLAME. 271 

The attentive student has ah'eady, it is hoped, found suf- 
ficient grounds, in the arguments and illustrations which 
have been presented, to admit the existence of a higher 
chemical philosophy than that of combustibles and support- 
ers. 

§ 462. In all cases of combustion the action is reciprocal* 
Hydrogen burns in common air ; but if a stream of oxygen be 
thrown into a jar of hydrogen, through a small aperture at 
the top, when the latter is burning, the flame is carried down 
into the body of the jar, and the oxygen will continue to 
burn in the hydrogen, as it issues from the jet. In this 
case the oxygen may be said to be the combustible, and the 
hydrogen the supporter. The simple statement in both cases 
is, that oxygen and hydrogen combine together, and com- 
bustion — that is, the disengagement of light and heat — is the 
consequence.* The diamond burns in oxygen gas ; but the 
latter is as much altered by the union as the former, and we 
cannot therefore say whether the oxygen or the carbon is 
the most burnt. Heat and light attend this union ; but the 
carbon of the human body is as truly burnt in the lungs by 
the atmospheric oxygen, as is the fuel of our fires ; and the 
product of the combustion (i. e. the carbonic acid) thrown 
out by the lungs at every exhalation, is the same thing 
which is discharged at the mouth of a furnace. In the 
case of the animal body, the combustion is so slow that no 
light is evolved, and only that degree of heat (98° to 100°) 
v/hich is essential to vitality. We cannot deny that there is 
in this case a real combustion, and yet it does not answer 
to our usual definition, since no light is evolved. The term 
combustion must have, then, a chemical sense vastly more 
comprehensive than its popular meaning. The rust which 
slowly corrodes and destroys our strongest fixtures of iron, 
and the gradual process of decay which reduces all struc- 
tures of wood to a black mould, are to the chemist as truly 
cases of combustion, as those more rapid unions with oxy- 



Why is this principle of classification radically deficient ? § 462. What 
is said of the reciprocal action of combustion ? Illustrate this by a jet 
of oxygen in hydrogen gas. The burning of the diamond. What is said 
of those cases where no light or heat accompanies the change '? 



* Daniell's Introduction to Chemical Philosophy, p. 322. 



272 NON-METALLIC ELETvIENTS. 

gen, which are accompanied by the splendid evolution of 
light and heat. 

^ 463. The heat produced hy combustion has received no 
satisfactory explanation. All we can say is, that any 
change of state in a body is accompanied by an alteration 
of temperature. When two liquids become solid, we can 
better understand why heat should be produced, (^ 109.) 
But why the union of carbon and oxygen, to form a gas, 
should evolve such intense heat as to fuse the most refrac- 
tory bodies, is more than has been explained. It will be 
remembered that chemical combination was pointed out in 
our enumeration {§ 79) as one of the sources of heat, and 
that it is strictly limited to the amount of matter suffering 
change. 

§ 464. The temperature at wldch bodies become luminous 
in diffuse day-light is considered to be about 1000°. Gases, 
however, can be heated much higher without being lumin- 
ous ; indeed it is probable that no degree of heat whatever 
would make common air or any other gas visible. We may 
heat a combustible gas, like the olefiant, to a point when it 
will take fire in the air. This we do in fact, when we 
touch it with the flame of a candle. The current of heated 
air ascending from an argandlamp chimney is invisible ; but 
a thin wire held in it will at once glow with bright red- 
ness, showing that the air is highly heated. A few bodies, 
when intensely heated in the air, suffer no change ; such are 
gold, platinum, palladium, and other metals not easily oxy- 
dized. The term incandescence expresses the condition 
of such bodies, and varies in intensity with the degree of 
heat. A white heat is considered equal to 3000°. A much 
lower temperature will inflame most combustible bodies, and 
the combustion being once begun, is continued without fur- 
ther addition of heat outward, as is seen in our com- 
mon fires. The atmosphere in such cases supplies all that 
is required to continue the combustion. 

§ 465. The structure of fiame deserves our particular at- 
tention. Flame is ignited, combustible, aerial matter. All 



§463. How is the heat of combustion explained? §464. At what 
temperature do bodies become luminous? How is it with gases? How 
is the high temperature of heated air made evident? How high is the 
temperature of whiteness? §465. What is flame? How does flame 
burn ? 



COMBUSTION AND FLAME.* 



273 




these conditions are needed to constitute flame, as a mo- 
ment's attention will show. The flame 
can burn only in contact with the 
air, and must therefore consist of 
an exterior ring or shell of flame, 
and an interior cone of uninflam- 
ed combustible matter. A com- 
mon candle or lamp shows those 
conditions perfectly. The wick 
draws up the tallow or oil, which 
is converted into a volatile hydro- 
carbon, as soon as it touches the 
ignited portion of the wick, or 
hot atmosphere of flame. This com- 
bustible can burn only in contact with oxygen ; and that the 
interior portion (a) is actually inflammable gas, is very ea- 
sily proved, since it can be led out by a small glass tube, (b,) 
and set fire to from its other end. In like manner, by bring- 
ing a sheet of platinum foil over the flame of a large spirit- 
lamp, it will be heated to redness in a ring, while the centre 
will remain black, shownngthat the interior is comparatively 
cold, and the exterior intensely hot. Phosphorus may be pla- 
ced on the expanded wick of a large alcohol-lamp, or on a tuft 
of cotton wet with alcohol, and after kindling, it can be at 
once extinguished, by setting fire to the alcohol, which, rising 
in a voluminous flame, envelops the phosphorus in an atmos- 
phere that cannot sustain its combustion, and consequently 
it ceases to burn, but commences again as soon as the air 
comes in contact with it. 

^ 466. The te?nperature of flame is much higher than that 
of ignited solids, even when the color of the flame is very 
feeble, as of alcohol or pure hydrogen. The quantity of 
light w^hich flames emit is dependent on the presence of 
minute particles of solid matter, which glow with intense 
heat and reflect a strong light. This result is experienced 
when the flame of the oxyhydrogen blowpipe falls on lime 
or platina ; and the brilliant focus of the galvanic light is 
probably filled with the vapor of volatilized carbon, or of the 
metals suflering combustion. The carbohydrogen gases burn 



Illustrate this in case of the common candle. How is the interior por- 
tion seen to be combustible ? Illustrate this by phosphorus. § 466. 
What is said of the temperature of flame ? On what does the luminous- 
ness of flame depend ? 



274 



*K^DN-METALLIC ELEMENTS. 



with such intense brilliancy, on account of the minute particles 
of carbon derived from the decomposition of the gas by the 
heat, which burn in the air, and thus give the strong light 
peculiar to these compounds. When the particles of free 
carbon become too numerous, and there is not oxygen enough 
to burn them, the flame smokes. A common tallow candle is 
in this condition, and must therefore be considered as a very 
imperfect means of illumination. The various contrivances 
in common use, as argand and solar lamps, &c., have for their 
object to raise the temperature of the flame so high, by a 
full supply of oxygen, as to leave no carbon unburnt. The 
quantity of light thus obtained from 
the same quantity of oil is greatly in- 
creased, and all inconvenience from 
smoke and bad odors avoided. 

The common laboratory lamp illus- 
trates this principle, as seen in the sec- 
tional figure. It will be observed that 
there is a central opening vertically 
through the lamp, which allows a 
u, column of air to draw up within the 
W^ circular v/ick, and the flame is thus 
doubled, as compared with a common spirit-lamp, or candle. 
^ 467. The student who resides where gas is used for 
illumination, possesses a ready means of 
procuring a very powerful and economical 
heat, which he can command at pleasure, 
by regulating its intensity with a stop-cock. 
It is always ready, and can be 
left for any length of time. 
With a mica chimney and a 
moveable foot connected with a 
flexible gas pipe, the gas-lamp 
may be placed where the con- 
venience of the operator re- 
quires. A small glass spirit-lamp with a close cover to pre- 
vent evaporation, is an indispensable convenience even in 
the humblest laboratory. 






Illustrate this. When the free carbon becomes too abundant, what 
happens? How do the argand and solar burners improve the quality of 
flame? What is the principle of this structure? §467. What is the 
gas-lamp? 



COMPOUNDS OF HYDROGEN. 



275 



^ 468. Dr. C. T. Jackson has contrived a modification of 
the common argand spirit-lamp, which is the most powerful 
lamp-furnace in use. This invention consists in applying 
the principle of the mouth-blowpipe to the argand-lamp, and 
is accomplished by forcing a blast of air, or of pure oxygen 
gas from a bellows, into the bottom of a tube within that 
which carries the circular wick. The arrangement is such, 
that the blast issues in a narrow ring concentric with the 
wick and in close contact with it. The wick is turned up 
pretty high, and the lower orifice of the argand tube stopped 
with a cork, when the blast is in use. By this lamp, 600 
grains of carbonate of soda are readily fused in a platinum 
crucible, and many operations accomplished which usually 
require a furnace heat. The supply of air or gas is regula- 
ted by a screw on the bottom of the blast tube, and the bel- 
lows to supply the blast is placed beneath the table and worked 
by the foot. If the intense heat is not wanted, the lower 
orifice is opened, and the lamp then becomes only a pow- 
erful argand. The chimney of this lamp must be made of 
mica, to withstand the heat. 

^ 469. The mouth-hlowpipe enables us 
flame of a com- 
mon candle or 
lamp into a pow- 
erful furnace 
heat. By the 
blast from the 
jet of the blow- 
pipe, the oper- 
ator turns the flame in a horizontal direc- 
tion upon the object of experiment, at the 
same time that he supplies to the interior 
cone of combustible matter a further quan- 
tity of oxygen. The flame suffers a remark- 
able change of appearance as soon as the 
blast strikes it, and the inner blue point has 
very different chemical effects from the ex- 
terior or yellow point. Immediately before 
the exterior flame is a stream of intensely 
heated air, which is capable of powerfully 
oxydizing a body held in it, and this point 
is therefore called the oxydizing flame. 

§ 468. Describe Dr. Jackson's lamp, 
blowpipe accomplish ? 





m 



§ 469. What does the mouth- 



276 NON-METALLIC ELEMENTS. 

The inner or blue point is called the reducing flame, and 
in it all metallic oxyds capable of reduction are easily redu- 
ced to the metallic state or a lower degree of oxydation. 
Between the centre and inner flames is a point of most 
intense heat, where refractory bodies are easily melted. 
Charcoal is generally employed to support bodies before 
the blowpipe flame, when we would heat them in contact 
with carbon. Forceps of platinum are used to hold the sub- 
stance when it is to be heated alone ; and a small wire of 
the same metal, with a little loop bent on one end, is used to 
hold a globule of fused carbonate of soda, or other flux, when 
we wish to submit a body to the action of such reagents. 
The art of blowing an unintermitting stream is soon acquired, 
by breathing at the same time through the nostrils ; and an 
experienced operator will blow a long time without fatigue. 
No instrument is more useful to the chemist and mineralogist 
than the mouth blowpipe. By its means we may in a few 
moments submit a body to all the changes of heat, or the action 
of reagents, which can be accomplished with a powerful 
furnace.* 

§ 470. The temperature of flame may he so reduced by 
bringing cold metallic bodies near it 
^^ as to be extinguished. On this sim- 

^^ pie fact rests the power of the " safety 

lamp" of Sir Humphrey Davy, to protect the life of the miner. 
If a narrow coil of copper wire be brought over a candle or 
lamp so as to encircle it, the flame will be extinguished ; 
but if the wire be heated previously to redness, the flame 
continues to burn. The same effect will be produced by 
a small metallic tube. A wire held in the flame is seen to 
be surrounded with a ring of non-luminous matter. If many 
wires in the form of a gauze, be brought near the flame of 
a candle, it will be cut ofl' and extinguished above ; only 
a current of heated air and smoke will be seen ascending, 
while the flame continues to burn beneath and heats the wire 



Describe the flame. How does the blast affect it? Distinguish be- 
tween the reducing and the oxydizing flames. § 470. How do cold me- 
tallic bodies affect flame ? What valuable instrument is based on this 
fact ? 



* The student would do well to consult '' Berzelius on the Blowpipe" 
translated by J. D.Whitney. Boston, 1845: Ticknor & Co.: J2mo 
pp. 237. , 



COMBUSTION AND FLAME. 



277 








gauze red-hot in a ring, marking the limits of the flame. 

The flame may be relighted above the gauze, and will then 

burn as usual, as seen in the second flgure. Sir Humphrey 

Davy found that a wire gauze would in all cases arrest 

the progress of flame, 

and that a mixture of 

explosive gases could 

not be fired through 

it. A wire gauze is 

only a series of very 

short square tubes, and 

their power to arrest 

flame comes from the fact that they cool the gases below 

their point of ignition. Providentially, the heat required to 

ignite the carbon gases is much higher than that which will 

produce the union of oxygen and hydrogen. 

§ 471. Safety Lamp. — The explosion of inflammable 
gases in coal-mines has destroyed thousands of those whose 
diities required them to submit to the exposure. 
To avoid these lamentable accidents, Davy 
invented the miner's lamp, which is only a com- 
mon lamp surrounded by a cage of wire gauze 
completely enclosing the flame. When this 
lamp is placed in an explosive atmosphere, the 
gas enters the cage, enlarges the flame on the 
wick, and burns quietly, the gauze eflectually 
preventing the passage of the flame outwards. 
We thus enter the camp of the enemy, disarm 
him, and make him labor for us. The miner 
is not only protected by this instrument, but is 
rendered conscious of his danger, by the enlarge- 
ment of his flame. As long as the lamp can 
burn, he feels it safe to stay, as an irrespirable 
atmosphere would extinguish the flame. The 
powerful blast of wind which sometimes sweeps 
through the mine may render the lamp unsafe, by forcing 
the flame against the gauze, until it is heated so hot as to 



How does wire gauze affect flames ? What may the wire gauze be 
considered? What temperature do the carbo-hydrogeiis require for 
their combustion? § 471. For what use was the miner's lamp contrived ? 
How is it constructed ? How does it indicate the state of the atmosphere 
in the mine ? 

24 



278 



METALLIC ELEMENTS. 



inflame the external atmosphere. This accident is pre- 
vented by the addition of a glass to cover the sides, the 
air being admitted from below through flat gauze discs. 

^ 472. The phenomena of the safety lamp may be easily 
illustrated by the teacher, with a large bell glass placed over 
a naked lamp and left open beneath. Hydrogen may be 
admitted from below by a gas pipe, when the atmosphere 
soon becomes explosive and goes off, extinguishing the 
lamp. The miner's lamp, under the same circumstances, 
will first burn with an enlarged flame, and then go out 
quietly, as soon as the air can no longer support the combus- 
tion. 

II. METALLIC ELEMENTS. 

1. General Properties of Metals. 

^ 473. The number of the metallic eleinents enumerated 
in our list (^181-2) is 43, which is more than three times the 
number of the non-metallic class, which has already engaged 
our attention. If we include the five lately proposed new 
metals, (§ 181,) we shall have forty-eight bodies in this class. 
Of all this number, however, a few only are of considerable 
interest, while many (at least half) are totally unknown in 
common life, and are familiar even to very few chemists. 
The minerals which contain several of the rare metals, in 
combination with various substances, are among the most 
uncommon specimens of mineralogical cabinets. It will not 
be proper, therefore, for us to dwell long on such substances 
as the student will almost certainly never see, although some 
of these bodies, in a purely chemical view, are very inter- 
esting, and they may in the progress of discovery become 
more common and have quite a number of important and 
useful applications.* 

§ 472. How are the phenomena of the safety lamp illustrated? § 473. 
What is the number of metallic elements ? How many of these are of 
much importance? 

* We may instance chrome as a case of this sort. It was known 
at first only as a curious and very rare red mineral (chroraate of lead) 
from Siberia, much valued by mineralogists, having been first observed 
in 1797 by Vauquelin. It is now found abundantly in union with iron, 
and is the source of several of the most brilliant and enduring pigments 
we have. Its chemical history is full of interest and inst^ruction. The 
same result may happen in other cases. 



GENERAL PROPERTIES OF METALS. 279 

^ 474. A metal is a body which conducts electricity and 
heat, which is opaque, and has a peculiar lustre, known 
as the " metallic lustre^ When submitted in solution to 
electrolysis, it is always oriven out at the negative side of 
the battery, and is therefore a positive electric. Any body 
which possesses these general properties is a metal, accord- 
ing to our present notions of the metallic character. We 
see every variety in some of these characters. Some metals 
are almost without lustre, as manganese, while others, like 
gold and silver, may stand as examples of perfection in all 
the metallic properties. Opacity is not complete even in 
gold and mercury, as we have already mentioned, (^ 53.) 
Some metals are perfectly malleable when cold, as silver, 
gold, lead, and tin ; others are malleable when hot, as iron, 
platinum, &c., and are not without this property, though in 
a less degree, even when cold. Some, like zinc, are lami- 
nable at a moderate heat, but brittle above and below it ; 
others, like antimony, are brittle at all temperatures short of 
fusion. We have already explained (§ 18) the properties 
of brittleness, malleability, ductility, and laminability. The 
tenacity of metals depends much on their relations to these 
properties. Iron is an example of great tenacity and duc- 
tility, while in malleability it is much inferior to gold and 
silver. 

§ 475. The tenacity of metals is compared by using wires 
of the same size of different metals, and ascertaining how 
much weight they will sustain. Iron is the most tenacious, 
and lead the least. Wires are drawn through ^-^ ^-^ 
smooth conical holes in a steel plate, each /©% /7\ 
succeeding hole being a little less than its © 1 » i 
predecessor. In this way wires of extreme 
fineness may be drawn from several of the 
ductile metals. Dr. Wollaston succeeded, by I ^ 
a peculiar method, in making a gold wire so W/ 
small that 530 feet of it weighed only one grain ; 
it was only -^-^-^-^ of an inch diameter ; and a platinum wire 
was made by the same philosopher, of not more than 3^0^ oo ^^ 



<^ 



§ 474. What is a metal ? How do they act in electrolysis ? What va- 
riety is seen in the metallic character? Is opacity perfect in them? 
Mention their characters. § 475. How is the tenacity of metals com- 
pared? Explain the use of the wire plate. How fine have wires of gold 
and platinum been made ? 



280 



METALLIC ELEMENTS. 



an inch. Metals passed repeatedly through the rolling-mill, 
or wire plate, become stiff and brittle, but are again made 
soft by heating them to redness and cooling them slowly. 
This is called annealing. Copper is annealed by plunging 
the red-hot metal into cold water, while the same treat- 
ment renders iron and steel extremely hard. 

§ 476. The fusibility and density of metals differ very 
much. The following table, compiled from Dr. Turner's 
Elements, and other sources, contains the density, points of 
fusion and dates of discovery of the most important metals. 
Some of those which are stated to be fusible above 3000^ 
require the heat of the oxy-hydrogen blowpipe to melt them, 
as platinum, for example. 



METAL. 


DENSITY. 


FUSIBILITY. 


DISCOVERED BY 


Platinum, 


20-98 


above 3000^ F., 


Wood, 1741. 


Gold, 


19-267 


2016° F, 


Long known. 


Tungsten, 


17-60 


nearly infusible, 


D'Elhuyart, 1781. 


Mercury, 


13-568 


—39°, 


Long known. 


Palladium, 


11-50 


fusible above 3000°, 


Wollaston, 1803. 


Lead, 


11-352 


6120, 


Long known. 


Silver, 


10-474 


1873 o, 


Long known. 


Bismuth, 


9-822 


4970, 


Agricola, 1530. 


Uranium, 


9- 


above 3000^, 


Klaproth,1789. 


Copper, 


8-895 


1996°, 


Long known. 


Cadmium^ 


8-604 


442° 


Stromeyer, 1818. 


Cobalt, 


8-538 


above 3000°, 


Brandt, 1733. 


Nickel, 


8-279 


above 3000°, 


Cronstedt, 1751. 


Iron, (pure) 


7-79 


above 3000^ 


Long known. 


Cast Iron, 




27860, 




Molybdenum, 


740 


above 3000°, 


Hielm, 1782. 


Tin, 


7-291 


4420, 


Long known. 


Zinc, 


6 86 


7730, 


16th century. 


Manganese, 


6-85 


above 3000°, 


Gahn and Scheel, 1784. 


Antimony, 


6-702 


above 1000<^ 


Basil Valentine, 1790. 


Tellurium, 


6-115 


above 6120, . 


Miiller, 1782. 


Arsenic, 


5-884 


unknown, 


Brandt, 1733. 


Columbium, 


5571 


above 3000°, 


Hatchett, 1802. 


Titanium, 


5-30 


infusible, 


Gregor, 1791. 


Sodium, 


•972 


190O, 


Davy, 1807. 


Potassium, 


•865 


136°, 


do. do. 



§ 477. Metals vary also in volatility as much as in other 

What is annealing? How is it accomplished in different metals? 
§ 476. How do the density and fusibility of metals compare ? Give 
some examples from the table. 



GENERAL PROPERTIES OF METALS. 281 

properties. Mercury boils at 662°, and arsenic, tellurium, 
cadmium, zinc, potassium, and sodium, are also volatile at 
temperatures short of a red heat. It is not impossible that 
all the metals may be volatile, if we could heat them highly 
enough; but many of them, as gold, platinum, silver, <fec., 
may be exposed to the highest heat of a wind-furnace with- 
out change. Some metals assume a semi-fluid or pasty con- 
dition before melting, such as platinum and iron, both of which 
can be welded or made to unite without solder, in virtue of 
this soft state ; lead, potassium, and sodium can be welded 
in the cold, as also can mercury, when it is made solid. In 
cooling from fusion some metals crystallize beautifully, of 
which bismuth is an example, while others, as gold and pla- 
tina, are not commonly seen in the crystalline form. 

^ 478. The metals are rarely found in their metallic state 
in nature. Their cViaracters are generally masked under 
some form of combination with oxygen or sulphur. Thus, 
iron is almost never seen in a malleable form in mines. 
The masses of malleable iron found on the surface of the 
earth are nearly all of meteoric origin, having fallen through 
the atmosphere to the earth. Some metals, as gold, silver, 
platinum, copper, bismuth, and a few others, are frequently 
found native, or in the malleable form, either pure or al- 
loyed with each other. An alloy is the union of two metals, 
as of copper and zinc, to form brass, and lead and tin, to 
make pewter, &c. Gold is usually found alloyed with sil- 
ver, and platinum has generally several rare metals alloyed 
with it. Alloys are chemical combinations, and are usually 
best suited to artificial purposes when made in the atomic 
proportions of the several metals. The alloys of mercury 
are called analgams. Copper and tin unite in several dis- 
tinct proportions, forming very unlike alloys, as gun and 
bell metal, and speculum metal. Several distinct com- 
pounds of gold with silver, and also of other metals, have 
been recognized. 

§ 479, In their chemical relations the metals are highly 

§ 477. How do metals compare in volatility by heat? Mention some 
of the volatile ones. What is said of the possible volatility of others? 
On what property does welding depend? What of the cryslallization of 
metals? §478. In what state do the metals occnr in nature? With 
what are they generally combined? Which are frequently in a metallic 
state? What are alloys ? Are they in atomic proportions ? W^hat are 
the alloys of mercury called ? 

24* 



282 METALLIC ELEMENTS. 

electro-positive, and as such form compounds with all the 
members of the oxygen group, and with phosphorus, car- 
oon, &c. They all unite with oxygen, and usually in more 
than one proportion, but their affinity for this element is 
very various. The majority of metals will combine slowly 
with the oxygen of the air, forming a coating of oxyd, (or 
rust,) which usually protects the metal from further action. 
This is the case with lead, zinc, copper, and iron. So- 
dium and potassium, and the metals of the alkalies gener- 
ally, have so strong an affinity for oxygen as to be able to 
decompose water at all temperatures. 

§ 480. The oxyds of the metals may be divided into three 
classes. 1st, the protoxyds, w^hich are strongly basic ; 
2d, those which are neither basic nor acid ; 3d, those 
which are decidedly acid in their relations. The changes 
of character in oxyds, have a uniform relation to the amount 
of oxygen they contain, the higher oxyds being either neutral 
or decidedly acid. Thus the protoxyd of manganese is a 
strong base, the deutoxyd is feebly basic, the peroxyd is 
indifferent, and the higher oxyds are the manganic and per- 
manganic acids ; which are capable of replacing sulphuric 
and hyperchloric acids. Arsenic, antimony, and tellurium 
have no protoxyds, and are remarkable for forming strong 
acids with oxygen. By this feature they are closely assim- 
ilated to the non-metallic bodies, and might with great pro- 
priety be classed, the two former in the nitrogen group, and 
the latter in the oxygen group, with sulphur, selenium, &c. 
We thus see the difficulty of drawing an exact line of 
division between the two classes of inorganic bodies, either 
by physical or chemical characters. 

§ 481. The compounds which the metals form with chlorine, 
iodine, sulphur, &c., bear a very striking analogy in com- 
position to the oxyds of the same metals. So true is this, 
that knowing what oxyds a given metal forms, we can al- 
most certainly tell what the composition of its chlorids, 
sulphurets, &c., will be. Thus the oxyds of iron being 



§ 479. In their chemical relations the metals are what? What is 
their affinity for oxygen? §480. How are their oxyds divided? What 
characters have these three classes ? On what does this character de- 
pend? Illustrate this in the case of manganese. What metals are re- 
markable for forming acids? To what are they thus assimilated ? § 481. 
To what are the metaUic chlorids analogous ? Illustrate this. 



GENERAL PROPERTIES OF METALS. 283 

FeO and Fe^Og, we find that the sulphurets of the same 
metal FeS and Fe^ S3, and the chlorids FeCl and Fe2 
01 3. There are some exceptions to this general rule, in 
cases where there are more sulphur compounds with a 
metal than there are oxyds. But the chlorids of a metal are 
never more in number than its oxyds. It might be inferred 
from this statement, that where these metallic bodies unite 
with acids to form salts, there would be the same conformity 
among them that is found among their bases, and such we 
shall find to be the fact. 

§ 482. Combinations of the metallic oxyds, chlorids, sul- 
phurets, &c., take place always among members of the same 
series, that is, oxyds with oxyds, chlorids with chlorids, sul- 
phurets with sulphurets, and so on : those members of the 
same series which differ greatly in character being most 
disposed to unite, as the oxygen acids with the oxygen 
bases, &c. Thus, sulphuric acid (a powerful oxygen acid) 
and protoxyd of iron (a powerful oxygen base) unite to form 
a salt which is entirely neutral, and in which the properties 
of neither constituent are sensible, having the formula 
FeO, SO3 for the dry sulphate of iron. 

§ 483. Compounds which belong to unlike or different 
series, on the contrary, do not unite, but often mutually de- 
compose each other. Thus, when hydrochloric acid and 
potash are brought together, both are decomposed, water and 
chlorid of potassium being formed, as may be understood 
from the following symbols : 

Potash. Hydrochloric acid. Water. Chlorid of Potassium. 

KO + HCl = HO + KCl. 

The latter remains in solution, and may be obtained in crys- 
tals on evaporation. 

§ 484. When any base unites with an acid to form a neu- 
tral salt, there must be as many equivalents of acid em- 
ployed, as there are of oxygen in the base itself. The same 
is true also of those acids which contain no oxygen, as the 

What inferences regarding the saline compounds of these bodies? 
§ 482. How do combinations among metallic oxyds, &c., take place ? 
Illustrate this by sulphuric acid and protoxyd of iron. § 483. Com- 
pounds which belong to different series act how ? Illustrate this by pot- 
ash and hydrochloric acid. § 484. What condition of neutrality is here 
stated in the formation of salts? How in case of hydrochloric acid? 
Illustrate this in case of peroxyd of iron and HCI. 



28^ METALLIC ELEMENTS. 

hydrochloric, provided the metallic oxyd dissolves in hydro- 
chloric acid without the evolution of chlorine. For exam- 
ple, peroxyd of iron dissolved in hydrochloric acid produ- 
ces water and a perchlorid of iron: 3HC1 and Fe^Og giv- 
ing rise to 3H0 and Fe.Clg. 

^ 485. Theory of Salts. — The binary compounds of chlo- 
rine, iodine, &c., with many of the metals, particularly those 
of the alkaline class, have in an eminent degree the properties 
of salts, and among them we recognize particularly the 
chlorid of sodium, or common salt, which is the parent, it 
may be said, of all salts, or that body from which they are 
all named. If the old definition of a salt, however, be ad- 
mitted, those bodies cannot be called salts, since according 
to that view a salt is a compound of the oxyd of a metal with 
an oxygen acid. To avoid this difficulty, two classes of 
salts have been constituted, the first of which includes all 
those binary compounds which, like common salt, have a 
metallic base in direct union with a salt-radical; and the 
second includes those salts which, like sulphate of soda, are 
supposed to be constituted of the oxyd of the metal and an 
oxygen acid. The first have been called the haloid^ salts, 
and the second the oxy-salts, 

§ 486. The term " salt-radical,^^ just employed, includes 
not only all the members of the oxygen group, except oxy- 
gen itself, but also all those compound bodies which, like 
cyanogen, and numerous similar substances, act the part of 
elements in the formation of compounds. Many of the most 
distinguished chemists of the present day insist on the exist- 
ence of a large class of these hypothetical compound radi- 
cals even in inorganic chemistry. 

^ 487. In stating the constitution of sulphuric acid, (^ 293,) 
it will be remembered that the expression SO^ + H was 
employed as an equivalent to SO3+HO. It is claimed 
that all the hydrated acids are in reality compounds of hy- 
drogen with a similar radical, and accordingly nitric acid 

§ 485. To what are the binary compounds of the oxygen group hke? 
What is the old definition of a salt? What two classes of salts have been 
mstituted to meet this difficulty? §486. What bodies are included un- 
der the term salt radical 7 § 487. What is the salt radical view of the 
composition of sulphuric acid 1 State the objections against, and reasons 
for, this view. 

* From hals, sea-salt, and eidoSi in the likeness of. 



GENERAL PROPERTIES OF METALS. 285 

will be NOg+H, instead of No^ + HO. The principal ob- 
jection to this view is that these hypothetical radicals have 
never been isolated. But we must not forget that the same 
is true of NO5, which is entirely an unknown body, and so 
are nearly all the organic acids. It is difficult to say what 
objection there is to admitting one hypothetical body more 
than another, when both are equally probable. Moreover, 
it is a fact worthy of particular attention, that those acids 
which are capable of existing dry and in a separate state, 
as sulphuric, (SO3,) phosphoric, (PO5,) and carbonic, 
(CO2,) are not acids as long as they remain dry, and al- 
though they form compounds with dry ammonia, these com- 
pounds are not salts. Sir Humphrey Davy long ago pro- 
posed to consider hydrogen as the real acidifying principle 
in all acids. This view of the case is, therefore, by no means 
new. What w^e now know of the metallic character of hy- 
drogen, goes to confirm his theory. If the salt radical 
theory is adopted, all acids will be considered as hydrogen 
acids, and all salts as haloid salts. For example, let us 
take two common saline bodies and present them according 
to these two views : 

Old view. New view. 

Sulphate of zinc, ZnO + SOg Zn + SO^. 

Nitrate of soda, NaO + NOs Na+NOg. 

^ 488. According to the new view, when an acid dissolves 
a metal, there is no necessity for supposing water to be de- 
composed. The metal takes the place of the hydrogen, and 
tlie latter is given off in a gaseous form ; or if the oxyd of 
the metal is used, the oxygen and hydrogen unite to form water, 
and no effervescence ensues. We shall consider the saline 
compounds of the metals under each, and not devote a sepa- 
rate part of the work to their discussion ; and our limits 
will compel us to be very brief, mentioning only those com- 
pounds which are the most important and interesting.* The 
nomenclature of the salts has already been explained, (§ 169,) 
and need not be repeated here. 

Give the constitution of sulphate of zinc and nitrate of soda on the old 
and new views. § 488. How, according to the new view, do metals and 
oxyds dissolve in acids ? 

* It is impossible to do justice to the binarj^ theory of salts in so 
limited a space as we allot ourselves, and the reader who wishes to seek 
further information, is referred to Mr. Graham's Elements of Chemistry, 
p. 158, English edition. 



286 METALLIC ELEMENTS. 

2. Classification of Metals, 

^ 489. An unexceptionable arrangement of the metals 
probably cannot be formed in the present state of our know- 
ledge. Some of these bodies, as we have already remarked, 
might be more properly classed with the first division of in- 
organic elements, while the principles of isomorphism would 
require us to bring together metals which have generally 
been arranged in distinct classes. Many authors divide the 
metals according to their power of decomposing water ; but we 
now know that this property is dependent in several instances 
on the condition in which the element exists, and that a metal 
may decompose water in one state but not in another. 
Others simply divide them into brittle and malleable metals. 
The order which we shall follow arranges the metals in 
a manner which is perhaps as unexceptionable as any other, 
and is generally the same with that adopted by Mr. Graham 
and Dr. Fownes, with some few exceptions. 

Class I. Metals of the Alkalies — 3 Metals and one Com" 
pound Metallic Radical. 

Potassium, Ammonium,* 

Sodium, Lithium. 

Class II. Metals of the Alkaline Earths — 4 Metals. 
Barium, Calcium, 

Strontium, Magnesium. 

Class III. Metals of the Earths — 7 Metals, 
Aluminium, Thorium, 

Glucinum, Cerium, 

Yttrium, Lantanum. 

Zirconium, 

Class IV. Metals whose oxyds form powerful bases — 10 

Metals. " 
Manganese, Zinc, 

§ 489. What is said of the classification of the metals? What classi- 
fication is followed here ? How many classes are made, and what are 
they ? 

* This hypothetical metal is placed in the order of real metals, from 
motives of convenience in considering its compounds. 



POTASSIUM. 287 

Iron, Cadmium, 

Chromium, Lead, 

Nickel, Uranium, 

Cobalt, Copper. 

Class Y. Metals whose oxyds are weak bases or acids — 

11 Metals. 

Vanadium, Bismuth, 

Tungsten, Antimony, 

Molybdenum, Arsenic, 

Columbium, Tellurium, 

Titanium, Osmium. 
Tin, 

Class VI. Metals whose oxyds are reduced by heat — 7 
noble Metals. 
Gold, Iridium, 

Mercury, Rhodium, 

Silver, Platinum. 

Palladium, 



CLASS I. METALS OF THE ALKALIES. 

I, potassium. 

Equivalent, 39 '19. Symbol, K, (Kalium.) Density, -865. 
^ 490. History. — Potassium was discovered by Sir Hum- 
phrey Davy in 1807, by means of the voltaic battery ; at 
the same time \vith its congeners, sodium, barium, strontium 
and calcium. Before that time the alkalies and alkaline 
earths were looked upon as simple elementary bodies, and 
were so treated in all chemical works. On passing the 
electric current through a cake of moistened potash, both 
electrodes being of platinum, violent action followed, oxygen 
was evolved with effervescence at the positive pole, and bright 
metallic globules, like mercury, accompanied by hydrogen 
gas, appeared at the negative pole. Some of these globules 
flashed and burnt with a violet light as they reached the 
air, and others remained and were soon covered with a 

§ 490. What is the symbol and equivalent of potassium ? When, 
and by whom, and how was it discovered? How is this metal found in 
nature ? 



288^ METALLIC ELEMENTS. 

white film that formed on their surfaces. These globules 
were the metal potassium, and its discovery, as well as that 
of its associates, constitutes one of the most interesting 
chapters in chemical history. 

Potassium in combination, chiefly as silicate of potash, is 
widely diffused over the globe. It forms a part of all fertile 
soils, and the chief source from which it is artificially pro- 
cured is the ashes of hard-wooded forest trees, which of 
course derive it from the soil on which they grow. It is 
also present in sea-water, as chlorid of potassium, and is 
found in the ashes of sea-plants. 

§491. Preparation, — The expensive and troublesome 
method of procuring this metal by galvanism has been 
replaced by a much more convenient and productive furnace 
operation, founded on the decomposition of potash at a 
white heat by charcoal. For this purpose carbonate of 
potash is intimately mixed with charcoal, which is best pre- 
pared by igniting cream of tartar in a covered crucible, which 
yields a black mass commonly known as *' black flux," con- 
sisting of carbonate of potassa, and charcoal derived from the 
organic acid. This mass is finely powdered, and one tenth 
part of charcoal in small lumps being added to it, the whole 
is quickly transferred to an iron retort, formed of a quick- 
silver bottle, and laid horizontally in a powerful wind 
furnace. A short iron tube connects the iron bottle with a 
copper vessel of peculiar construction, containing naphtha, 
and kept cold. The bottle is then gradually raised to an 
intense heat, having been previously protected by a well- 
dried coat of sand-luting, to guard the iron against 
fusion. Decomposition of the carbonate of potash follows, 
carbonic oxyd gas escapes, and metallic potassium distills 
over in melted globules, which fall into the naphtha, where 
they are preserved. Many precautions are required to en- 
sure success, and particularly to see that the tube of deliv- 
ery does not become stopped ; to guard against which, the 
apparatus is so constructed that a strong iron rod can be 
thrust into the opening to clear the way. 

The first product is not pure, and must be redistilled in a 
small iron retort, with a little naphtha into a receiver con- 
taining that liquid. It is requisite to employ naphtha in this 

§ 491. How is potassium prepared? Describe the arrangement. How 
is the metal preserved ? 



POTASSIUM. 289 

process, because it contains no oxygen in its constitution, 
and does not suffer change readily from the action of the 
potassium. 

§ 492. Properties, — Potassium, when recently obtained, 
is a brilliant, silver-white metal, possessing the metallic lus- 
tre in an eminent degree. At common temperatures it is 
soft like putty, and may be easily moulded or welded by the 
fingers. It is the lightest metal known, having a density of 
only -865 ; consequently it floats on water, for the oxygen of 
which it has so great an affinity as to decompose it at all 
temperatures. It burns brilliantly on the surface of the 
water with a beautiful violet purple flame, and is rapidly 
propelled over its surface by the gases and vapors evolved 
in the combustion, forming one of the most attractive of chem- 
ical experiments. The hydrogen of the decomposed water 
also burns at the same time. Any considerable quantity 
thrown on water will explode violently, scattering the 
burning metal in all directions. Exposed to the dry air, 
it soon tarnishes, and gradually falls to a white powder. 
Its metallic lustre may be beautifully seen by melting it 
under naphtha, when it is extremely brilliant. At 30° it is 
brittle and crystallizes in cubes ; at 150° it melts, and 
below redness it boils and is raised in vapor. Consequently 
it may be distilled unchanged in vessels freed from oxygen. 

§ 493. The uses of potassium are purely scientific. It is 
a most powerful means of research, since its affinity for oxy- 
gen is so great as to enable it to decompose the chlorids of 
aluminium, glucinum, yttrium, thorium, magnesium; and zir- 
conium, yielding tg us the metallic bases of these compounds. 
It is also, as will be remembered, (^ 355 and ^ 367.) the 
means by which silicon and boron are obtained. 

1. Compounds of Potassium with the Oxygen Group. 

^494. Potassium combines with all the members of the first 
class, forming bodies several of which are of great importance 
in the arts and in pharmacy. Those which we shall men- 
tion are — 



§ 492. What are its properties ? Give its density. What is its strong- 
est affinity ? What is its action on water ? How does air affect it ? 
How does heat affect it? §493. What are its uses? What other bodies 
have been produced by its means? §494. Name the compounds of 
potassium with the oxygen group. 

25 



290 



METALLIC ELEMENTS. 







Composition by weight. 


Symbol. 


Combining No. 


Potassium, 


Oxygen. 


KO 


47-19 


39 19 


8 


K03 


63-19 


3919 


24 

Chlorine. 


KOCl 


74-50 


39-19 


35-41 

Bromine. 


KBr 


117-45 


39-19 


78-26 

Iodine. 


KI 


165-55 


39-19 


126-36 

Fluorine. 


KF 


57-89 


3919 


80-70 

Sulphur. 


KS 


55-28 


39-19 


16-09 


KS, 


119-64 


39-19 


80-45 

Selenium. 


KS 


78-96 


3919 


39-57 



Oxyd of Potassium, 
Peroxyd do., 

Chlorid, 

Bromid, 

lodid, 

Fluorid, 

Sulphuret, 
Persulphuret, 

Seleniuret, (probably,) 

§ 495. The oxyd of potassium is formed only when 
potassium is exposed to dry oxygen or common air. It is a 
white powder, strongly alkaline, which has a great affinity 
for water, forming with it three distinct hydrates, the first 
of which is caustic potash, (KO, HO.) This hydrate is a 
white solid, which fuses at a temperature near to redness ; 
but no degree of heat will expel the equivalent of water 
with which it is combined. On cooling, it forms a some- 
what crystalline, compact mass, which has a great avidity 
for water, attracting it rapidly from the atmosphere. Half 
its weight of water will dissolve it, and it is also soluble in 
alcohol. It is best prepared by decomposing pure car- 
bonate of potash, dissolved in 10 parts of water in a clean 
iron vessel, with half its weight of good quick-lime, previously 
slaked and mingled with so much water as to form a thin 
paste, called milk of lime. This is added in small portions 
to the potash solution while the latter is boiling, a short inter- 
val being allowed between each addition ; all the lime being 
added, the whole is boiled for a few minutes and then is re- 
moved from the fire and covered up. Care is needed to keep 
the solution dilute, to prevent the caustic potash formed from 
decomposing the resulting carbonate of lime. After standing 
a few hours until all the lime has settled and the liquid is 



§ 495. How is its ox5^d formed ? What is its hydrated oxyd called ? 
What are the properties of the hydrate of potash? How is it pre- 
pared ? 



COMPOUNDS OF POTASSIUM. 291 

clear, it is drawn off by a syphon, and concentrated by 
boiling in a clean iron pan or silver capsule, until it has an 
oily consistence, when it is poured out upon a clean surface 
of iron or marble ; it then hardens into the white solid 
hydrate called caustic potash. To insure its purity, it may 
be dissolved in absolute alcohol, which will leave behind 
its impurities. The alcohol is expelled from the decanted 
solution by heat, and the solid potash recovered by fusion in 
a silver crucible. The moderately strong solution of potash 
answers most of the purposes of the laboratory as well as 
the solid. 

§ 496. The solution of caustic potash is intensely alkaline, 
saturates the most powerful acids, restores the colors of red- 
dened vegetable blues, and turns many of them green ; it has an 
acrid and most disgusting taste peculiar to alkalies, and, when 
strong, attacks all organic matters, dissolving and disorgan- 
izing them. Its solution feels soapy on the fingers, and 
forms compounds with fats, called soaps. The solid potash 
is often used as a caustic by surgeons, whence its name. 
Silica is dissolved by it. Its solution absorbs carbonic acid 
perfectly, and is greatly used for that purpose in organic 
analysis ; the solid potash removes not only carbonic acid 
but also moisture from the air ; it is therefore sometimes 
used in desiccation. It is a valuable manure in small quan- 
tities — nearly all good manures containing a notable amount 
of it. Its constant presence in plants would lead us to ex- 
pect this. 

^ 497. The presence of potash in solution may be detected 
by using an alcoholic solution of the double chlorid of 
platinum and so'dium, which throws down a yellow, crystal- 
line precipitate in a concentrated solution. Perchloric, tar- 
taric, and hydrofluosilicic acids are also tests of the presence 
of potash, which forms with all of them precipitates but little 
soluble in water. 

§ 498. Peroxyd of potassium is an orange-yellow powder, 
formed by passing oxygen over potash heated to redness in 
a tube. It is decomposed by water, oxygen being given 
off, and a solution of potash remaining. 

To ensure its entire purity, how is it treated ? § 496. What are the 
properties of its solution? What compounds does itform with fats ? AVhy 
is it called caustic 7 Name some of its other uses and properties. 
§497. How is its presence detected? §498. Peroxyd of potassium is 
how prepared? 



292 METALLIC ELEMENTS. 

§ 499. Chlorid of Potassium may be formed by the direct 
combustion of potassium in chlorine gas, which takes place 
spontaneously. Also by dissolving potash in dilute hydro- 
chloric acid to saturation, when cubic crystals of chlorid of 
potassium are obtained on evaporating the solution. It is 
also left as a residuum after the oxygen process, (^ 252.) It 
has a bitter saline taste, and does not preserve meats, like 
the chlorid of sodium. 

§ 500. Bromid of Potassium is prepared by saturating a 
solution of potash with bromine, evaporating the solution 
and igniting the residuum in a covered crucible of platinum 
or iron. The melted mass is bromid of potassium, and may 
be turned out to cool on an iron plate. In the solution, both 
bromate of potash and bromid of potassium exist, but the 
ignition expels oxygen, and only the bromid is left. It is a 
white soluble salt, which crystallizes in cubes, and is also 
soluble in alcohol. The crystals are anhydrous, and decrep- 
itate when heated, like common salt. Bromid of potassium is 
frequently found in the waters of saline springs and inland 
seas. 

^501. lodid of Potassium, formerly called hydriodate 
of potash, is a compound of great use in medicine, being in 
fact the form in which iodine is usually employed in medical 
practice. It is formed precisely like the bromid just 
described, and also by decomposing the iodid of iron, by a 
solution of potash. It is a white salt in cubic crystals, very 
soluble in both alcohol and w^ater. Its solution dissolves a 
large quantity of free iodine, acquiring thus a deep brown 
color. 

^ 502. Fluorid of potassium is obtained by the action of 
hydrofluoric acid on potash. It is perfectly analogous to the 
preceding salts, crystallizes in cubes, and is very soluble in 
water. 

^ 503. Sulphuret of Potassium. — Sulphur combines with 
potassium in several proportions— probably in seven. The 
protosulphuret of potassium is made by melting together its 
constituents, or better by passing hydrogen over the neutral 

§ 499. How is its chlorid made, and what are its properties? § 500. 
Describe the formation of bromid of potassium. 4 ^^l- What use is 
made of iodid of potassium? What are its properties? § 502. Fluorid 
of potassium is how prepared ? What crystalline form is common to all 
the foregoing salts? § 503. What are the compounds of sulphur and 
potassium ? 



COMPOUNDS OF POTASSIUM. 293 

sulphate of potash heated to redness. Water is formed, and 
sulphuret of potassium remains. It is a bright red solid, and 
forms a colorless solution in water, which has an alkaline 
reaction. This is a sulphur base of considerable power, 
and combines with sulphur acids without decomposition. 
Other acids decompose it with the escape of sulphureted hy- 
drogen. The trito sulphuret of potassium (KS3) corresponds 
to the teroxyd of the same base. 

^ 504. The pent a sulphuret of potassium ( persulphuret) is 
formed when sulphur is fused with carbonate of potash at 
as low a heat as possible ; hyposulphite of potash is formed 
at the same time. The persulphuret is a deep orange- 
yellow solid, soluble in alcohol. 

The protosulphuret is converted into the persulphuret by 
boiling in water with four equivalents of sulphur. 

The seleniurets of potassium are supposed to be like the sul- 
phurets, but they are not much known. 

2. Compounds of Potassium with the other Non-Metallic 
Elements. 

§ 505. Nitrogen forms a compound with potassium, (K3N.) 
When potassium is heated in dry ammonia, an olive-green 
solid is formed, which is a compound of amidogen and potas- 
sium, (K, MH^.) When this is heated, ammonia escapes 
and a gray body resembling graphite is left behind ; this is 
the compound in question. Phosphorus also forms a solid 
compound with potassium — the phosphuret of potassium—- 
which is decomposed by water with the escape of spontane- 
ously inflammable phosphureted hydrogen. 

Unimportant, and almost unknown compounds, are also 
formed by potassium with carbon and hydrogen ; but no com- 
pound is known between it and silicon and boron. 

3. Salts of Potash, 

§ 506. The salts of potash are numerous and important. 
We shall however mention now only the carbonates, sul- 
phates, nitrate, and chlorate. As it will be altogether im- 



Describe the protosulphnrets. § 504. The pentasulphnret is what, and 
how formed? § 505. What is the compound of nitrogen and potassium, 
and how formed? What other compounds of potassium with non-metallic 
elements are named ? 

25* 



294 METALLIC ELEMENTS. 

possible to enumerate even the names of all the salts of 
the metals, we must content ourselves with a selection of the 
most important and interesting. 

^507. Carbonate of Potash, KO, CO2+2KO, (69-19.)— 
This salt, in an impure form, is made on a great scale in this 
country, under the wdiXne o{ pearlash d^ndi potash,, which is the 
alkali obtained from the ashes of forest trees, by lixiviation 
and combustion. 

The crude article of commerce is contaminated by sili- 
ca, sulphate of potash, and chlorids of potassium and sodium. 
The latter impurity is frequently added in the process of 
manufacture, either through ignorance, or from fraudulent 
motives. The best potash is made by using hot water to 
lixiviate the ashes, in small leach-tubs. The brown mass 
left by evaporating the lixivium to dryness in iron kettles, 
is the potash of commerce. This is moderately calcined to 
burn off the coloring matter, when a spongy mass of a fine 
light blue color is left, which is the pear lash. 

§ 508. The pure carbonate is best obtained by calcining 
the cream of tartar, (acid tartrate of potash,) and dissolving 
out the carbonate from the coaly mass by water. The fil- 
tered solution is evaporated to dryness in a silver capsule, 
and the s^lt obtained pure. 

The carbonate of potash has a strong alkaline taste, turns 
cabbage or dahlia paper green, and is somewhat caustic ; it 
dissolves in about twice its weight of water, forming a solu- 
tion, which is much used in the laboratory. It crystallizes 
with difficulty, and takes up two equivalents of water in so 
doing. It is quite insoluble in alcohol. This is a very de- 
liquescent salt, and must be kept in well-stopped bottles. 

Even when most pure it is apt to contain a trace of silica, 
from which it can be freed by igniting the bicarbonate, and 
evaporating its solution to dryness. 

^ 509. Alkalimetry. — The great use that is made of potash 
and soda in the arts, by soap-boilers, glass-makers, and oth- 
ers, renders it very important that some easy and expeditious 



§ 506. What is said of the salts of potash, and which will be now con- 
sidered ? § 507. What is the formula and atomic number of the carbon- 
ate of potash ? What crude forms of it do we know ? How is the crude 
article prepared? How does pearlash differ from potash ? §508. How 
is the pure carbonate obtamed ? What are its properties ? § 509. What 
is alkalimetry? 



SALTS OF POTASH. 295 

method should be known, by which the value of any sample 
of alkali may be at once determined. This object is easily 
accomplished by ascertaining how much acid of known 
strength is required to exactly neutralize a given weight of 
the specimen to be analyzed. I'he amoui#of acid is of 
course equivalent to the amount of alkaline base present. 
This object is accomplished by using the alkalimeter^ which 
is a glass measure about 14 inches long, holding 1000 
grains of pure water at 60^. It is graduated into 100 
equal parts, so that each graduation is equal to 10 
grains of water. Sulphuric acid is employed of such 
strength, that one degree of the alkalimeter is sufficient 
to neutralize exactly one grain of pure potash, (or soda, 
as the case may be.) Acid of this strength is pro- 
cured as follows : 146*61 grains of pure dry carbon- 
ate of potash are dissolved in four or five ounces of 
hot water. This quantity contains exactly 100 grains 
of pure potassa. The alkalimeter is now filled v^ith 
dilute sulphuric acid, (say 1 part acid to 10 water,) and 
turned very gradually into the potash solution, until 
a piece of blue test paper floating in it begins to red- 
den. We then know that the alkali is all neutralized, 
and having carefully observed how many measures of 
acid have been used, we find that 83 (for example) 
are consumed. , We now know that 17 measures more 
of water are required to make our dilute acid of such 
strength that 100 measures of it shall equal 100 grains of 
pure potash ; it is diluted accordingly, and we then have a 
test acid, of which 1 measure in the alkalimeter is equal to 
1 grain of pure potash. 100 measures of such acid would 
therefore neutralize 59 grains of dry carbonate of potash, or 
47 grains of crystallized carbonate. 

All that is necessary, therefore, to tell the real value of a 
sample of crude potash, is to weigh out 100 grains of it, 
dissolve it in water, filter if necessary, and then observe how 
many measures of the test acid are required to neutralize it. 
Suppose that 76 are required, then we know that there are 
76 parts of real alkali in 100 parts of the sample, or 76 per 
cent, of it is available. An analysis of this sort can be per- 
formed in a very short time, hardly longer than is required 

Describe the alkalimeter, the test acid, and its mode of preparation. 
How is the real value of a sample of potash told by this instrument? 



296 METALLIC ELEMENTS. 

to read this description. Of course the same process is 
good for soda, substituting the equivalent numbers of soda 
and its compounds for those of potash. 

^510. Several samples of American potash examined by 
Dr. L. C. Befll yielded 73-6 ; 74-6 ; 75 and 769 per cent, 
of carbonate and hydrate of potash ; from 6 to 15 per cent, 
of chlorids of potassium and sodium ; with from 1 to 15 per 
cent, of insoluble matter.* 

§511. Bicarbonate of Potash, (KO, CO^+HO, CO^,) 
Equiv. 100*19. — This salt is formed by passing a stream of 
carbonic acid gas through a cold solution of carbonate of pot- 
ash. It crystallizes in large and beautiful crystals referable 
to the right rhombic system. Four parts of water dissolve 
it ; the solution has an alkaline taste and reaction, and is 
not caustic ; by heat it is again converted to the simple car- 
bonate, and it loses one equivalent of carbonic acid by solu- 
tion in hot water. 

§ 512. Sulphate of Potash, KO SO3, Equiv. 87-28.— This 
salt is usually prepared by neutralizing the residue of the nitric 
process, (§ 310,) and is also procured by saturating a con- 
centrated solution of potash by strong sulphuric acid, added 
drop by drop. It is an anhydrous, well crystallized salt, which 
decrepitates with heat, and has a density of 2-4. It re- 
quires 100 parts of water to dissolve 8*36 parts of this salt 
at 32^, and 0096 parts more for every degree above that. 

§ 513. Bisulphate of Potash, or Hydrate of Bisulphate, 
(sulphate of water and potash,) KO, SO3 + HO, SO3, Equiv. 
137-37. — This salt is obtained by decomposing nitrate of po- 
tassa by two equivalents of oil of vitriol, in the process for 
nitric acid. It cools into a white crystalline mass at 386°'6, 
which is very soluble in water, with partial decomposition. 
It is dimorphous in crystalline form, one of its figures being 
identical with crystallized sulphur. The solution is strongly 
acid, and acts on bases nearly as powerfully as if potash were 
not present. 



§ 510. What did the samples of American potash examined by Dr. 
Beck yield? §511. What is the bicarhonate of potash? Give its for- 
mula. What are its properties? § 512 Sulphate of potash has what 
formula? How is it prepared? §513. Give the formula of bisulphate 
of potash and its properties. 



* Beck's Manual of Chemistry, p. 228, 2d edition. 



SALTS OF POTASH. 297 

§ 514. Sesqitisulphate of Potash,2KO,SO^ + llO,SO^,— 
This salt is obtained from the nitric acid residue, in fong 
silky needles, which resemble asbestus. They cover the 
previous salt after long standing, with a beautiful vegetation 
or efflorescence. 

§ 515. Nitrate of Potassa ; Saltpetre ; Nitre; KO, NO^, 
Equiv. 101*19. — This important salt is a natural product in. 
the hot and dry regions of India and South America, being 
formed by the gradual decomposition of animal matters in 
the soil. It is also formed artificially by heaping together 
beds of old mortar, earth, dung, and other animal matters, 
and occasionally wetting the mass with fermenting urine. 
In some of the caverns in Kentucky, the soil on the floors 
becomes strongly impregnated with nitrate of lime, which is 
decomposed by wood ashes, nitrate of potassa being formed. 
In all these cases, the nitre is^obtained by lixiviating the 
nitrous earth with water, evaporating and crystallizing the 
solution, redissolving and crystallizing a second time, until 
the salt is obtained pure. 

^516. Properties. — Nitre crystallizes in long, six-sided 
prisms, with dihedral summits, being a modification of the 
right rhombic prism ; is anhydrous, and fusible at a heat 
under redness. It is unaltered in the air, insoluble in alco- 
hol, but dissolves in about 3 parts of water at dO'^, In hot 
water it is much more soluble, 100 parts of water at 206°'6, 
dissolving 236 parts of the salt. Its solution has a cooling 
taste, and some antiseptic properties. . 

§ 517. The great quantity of oxygen contained in nitre, 
and the ease with which it parts with it, render it a val- 
uable reagent. It is the chief constituent of gunpowder, 
imparting oxygen to the carbon and sulphur in that com- 
pound, to form with explosive energy those gases which are 
generated by the combustion of the materials. It is also 
much used in all pyrotechnic mixtures, as well as to defla- 
grate and scorify metals. The surface of silver ware is 
often scorified by nitre, which burns out the alloyed copper, 
and leaves a surface of pure silver. Good gunpowder is 



§ 5J4. What is sesquisulphate of potash ? § 515. Where is the nitrate 
potash found? How is it formed artificially? How is it procured from 
the nitrate of lime? §516. What are the properties of nitre? (^517. 
What renders nitre a valuable reagent? Of what is it the chief constit- 
uent? 



English. 


Prussian. 


]25 


11-5 


12-5 


13-5 


75- 


75- 



298 METALLIC ELEMENTS. 

composed very nearly of 1 equivalent of nitre, 3 of carbon, 
and 1 of sulphur. Thus : 

Theoretical mixture. 

Sulphur, 11-9 

Charcoal, 13 5 

Nitre, 74-6 

Much of the explosive energy of gunpowder depends on 
its granulation ; a fine dust of the same composition with 
powerful powder, burns with a rapid deflagration, but with- 
out explosion. The gases formed from its combustion are 
carbonic acid and nitrogen, while sulphuret of potassium 
remains as a solid residue. The combustion of a squib, or 
moist gunpowder, gives a much more complicated result ; 
nitric oxyd, sulphureted hydrogen, carbonic acid, carbonic 
oxyd, nitrogen, and other products, being formed. The con- 
stitution of gunpowder is varied according to the use for 
which it is intended. Thus, 20 sulphur, 15 charcoal, and 
65 nitre, are used for blasting-powder, and its combustion 
is rendered still slow^er by mixing it with several times its 
bulk of saw-dust. The effect then is more powerful in 
moving large masses of rocks. 

§ 518. Nitrate of potassa has been much used in England 
as a manure, and, as already mentioned, (310,) is the source 
of the best nitric acid. It is also employed (^ 253) to yield 
oxygen gas, 

^519. Chlorate of Potash, KO, ClO^, Equiv. 122-60.— 
This is the«salt already named (^ 252) as the best source of 
pure oxygen gas, of which it yields a great quantity by heat 
alone. It is formed by passing chlorine gas through a 
strong solution of carbonate of potash, chlorate of potash 
and chlorid of potassium being formed, the chlorate being 
easily crystallized out by its less solubility than the chlorid 
of potassium. The reaction is between 6K0 + Clnr5KCl-f 
KO, CIO5. It is also formed by decomposing the chlorate 
of lime, resulting from injured bleaching-powders. 

§ 520. Properties. — Chlorate of potash crystallizes in 
flat tables referable to the oblique rhombic prism, and has a 



What is the constitution of gunpowder ? On what does its explosive en- 
ergy depend ? What are the products of its combustion ? If wet, what 
are they? How is blasting-powder made more efficient? § 518. What 
other uses of nitre? § 519. What is chlorate of potassa, and how 
forn:ied ? § 520. What are its properties ? 



SODIUM. 299 

pearly lustre. In cold water (30°) it is very little soluble, 
and 100 parts of water at 60° dissolve only 6 parts of the 
salt. Its taste is cooling and disagreeable, resembling nitre. 
It fuses below redness, oxygen being given off, and chlorid 
of potassium is left behind. 

^521. With combustible bodies its action is more ener- 
getic than that of nitre. With sulphur and charcoal it forms 
a compound that explodes by friction, and was formerly 
much used in the manufacture of * lucifer' matches. With 
sulphur alone, it detonates powerfully when wrapped in a 
paper and struck by a hammer. With phosphorus its reac- 
tion is extremely violent ; a deafening explosion follows the 
slightest compression of the ingredients, and burning phos- 
phorus is projected in all directions. 

All attempts to form a gunpowder of chlorate of potash 
have failed, the action of the mixture being so violent as to 
lend asunder the arms employed. A mixture of sugar and 
chlorate of potash is instantly inflamed by a drop of sulphu- 
ric acid. 



II. SODIUM. 

Equivalent, 2327. Symbol, Na. {Natrium,) Density, '972. 

§ 522. Sodium was discovered by Davy soon after the dis- 
covery of potassium, and in the same way. It is prepared 
by a furnace operation, quite similar to that already de- 
scribed (§ 491) for potassium; the carbonate of soda and 
charcoal being used in place of the carbonate of potassa. 

This metal forms more than 40 parts in 100 of common 
salt, and is also frequent in various combinations in the min- 
eral kingdom. The ashes of sea-plants afford it largely, as 
crude carbonate of soda. 

^ 523. Sodium is a white metal, with a silver brilliancy, 
and much resembles potassium in its general properties. Its 
density is -972, and it melts at 194°. At common temper?- 
lures it is much harder than potassium, but is easily mould- 
ed in the fingers. It does not inflame on cold water, but 
moves about rapidly in a brilliant sphere, until it is all con- 



§ 521. What is its reaction with combustibles ? Can gunpowder be 
made from it? § 522. Who discovered sodium, and how is it prepared ? 
§ 523. What are its properties ? 



200 METALLIC ELEMENTS. 

sumed. It may be alloyed with potassium by simple press- 
ure, and is then inflamed on water, or alone on hot water, 
burning with a bright yellow light, characteristic of sodium. 
The same color is seen when a piece of soda-glass, or 
any mineral containing soda, is held in the flame of the 
blowpipe ; the flame is instantly tinged yellow. Exposed 
to the air, sodium soon falls to a white powder of oxyd 
of sodium. 

The compounds of sodium are so similar to those of po- 
tassium, that we can pass them with a brief mention. 

^ 524. The oxyd of sodium, NaO Equiv. No. 31-19, is 
formed by decomposing the carbonate, by the same means 
employed to form the caustic potash, (^ 495.) It is a strong 
alkali, and very caustic. All its salts are soluble, by which 
it is distinguished from potash, whose chlorid forms an in- 
soluble compound with chlorid of platinum. 

^ 525. Chlorid of Sodium ; Sea Salt ; Common Salt ; NaCl, 
58*68. — This familiar and abundant salt is too well known, 
to need much description. It is formed when sodium takes 
fire in chlorine gas, as well as when soda or its salts are 
neutralized by hydrochloric acid. Common salt forms 
about 27 of every 1000 parts of sea-water, and in warm 
climates, especially in the West Indies, sea-water is evap- 
orated in large quantities by the sun's heat, to obtain salt. 
Numerous saline springs are found in New York, Ohio, Ken- 
tucky, and other places in this country, (^ 458,) which aflford 
vast quantities of salt by evaporation. The brine springs 
in Onondaga county, N. Y., are among the most valuable, 
and have been worked since 1789. This water contains 
one seventh part of dry sah. 

^ 526. Common salt crystallizes in cubes, is anhydrous, 
and crackles or decrepitates when heated. It requires 2-7 
parts of water for its solution, and is equally soluble in 
hot and cold water. Its density is 2-557, and in pure alco- 
hol it is scarcely at all soluble. It fuses at redness, and 
siiblimes in vapor at a higher temperature. It is employed 
for this reason to glaze earthen ware, since its vapor is de- 
composed by the oxyd of iron of the clay, chlorid of iron 
being driven ofl", while soda unites with the silica of the 
clay to form the glaze. 

§524. What is its oxyd? How is it distinguished? §525. Describe 
common salt. How is it procured ? How much does sea-water con- 
tain? § 526. Give the properties of salt. How does it act as a glaze? 



COMPOUNDS OF SODIUM. 301 

The hromids and iodids of sodium are also cubical salts. 

§ 527. Carbonate of soda is manufactured on a very great 
scale from common salt. {§ 420,) and is found nearly 
pure in the arts. It crystallizes in an oblique rhombic 
prism, and has ten atoms of water of crystallization, (NaO, 
CO2 + IOHO.) This salt is sometimes found native. The 
common form of carbonate of soda is a dry powder, called 
salts of soda^ which is an impure mixture of chlorid, sul- 
phate, &c. The pure salt has 58-58 per cent, of soda, and 
41*42 of carbonic acid. The value of the commercial ar- 
ticle is ascertained by the alkalimeter already described. 
Carbonate of soda dissolves in about 5 parts of water, and 
the solution has a disagreeable alkaline taste. 

§ 528. Bicarhonateof Soda,Yi.O,Q,0,^-\-^^^,QO^^, Equiv. 
84-27. — This salt is formed when carbonic acid is passed 
through a saturated solution of the neutral carbonate. It is 
deposited in a dry white powder, which requires 13 times 
its weight of cold water to dissolve it. Its taste is alkaline, 
but much less disagreeable than the pure carbonate. 

This salt is thrown down as a granular precipitate, when 
bicarbonate of ammonia is added in fine powder to a solution 
of an equal weight of common salt. 

^ 529. The sesquicarhonate of soda, 2NaO + 3C02-f- 
4H0, is a compound which occurs in nature, being found 
with other' saline matters in Africa and South America. 
The natural salt is called trona ; it is little soluble, and unalter- 
able in the air. Its crystals are right rhomboidal prisms. 

^ 530. Sulphate of Soda, Glauber's Salt, NaO SO3 + lOHO. 
Equiv. 71-33 + 90. — This salt is the result of the hydro- 
chloric acid process, (§ 417,) and is also found native, 
and in solution in natural waters. It fuses in its own 
water of crystallization, on application of heat, and loses 
its water (effloresces) on^ exposure in dry air. Water dis- 
solves half its own weight of sulphate of soda at 9P, but 
only 42*65 parts at the boiling temperature. 

A saturated solution may be cooled under a film of oil, or 
in a vessel corked tight while hot, and when it is cold 

§ 527. From what is carbonate of soda chiefly made ? What are its 
properties and constitution ? § 528. How does the bicarbonate differ 
from the carbonate of soda? What are its properties? §529. What is 
the sesquicarhonate ? § 530. Give the composition of sulphate of soda. 
What of its solubility ? How does its saturated solution act if cooled 
away from contact with the air ? 

26 



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':anfs. ■ 



TW • 



BIZ af 



-JIZL, t; BFj 



iJMkz: 






(SE«>1] 



fiODiux. 303 

rnombic prisms-, which are efflorescent. The crystals dis- 
solve in 4 parts of cold water, and undergo the aqueous 
fusion when heated. The salt is bitter and purgative ; its 
solution is alkaline to test-paper. 

-4 second trihasic phosphate^ sometimes called sub-phos- 
phate, oNaO, P0^4-24HO, is obtained by adding solution 
of caustic soda to the preceding salt. The crystals are 
slender six-sided prisms, soluble in 5 parts of cold water. 
It is decomposed by acids, even the carbonic, but suffers no 
change by heat, except the loss of its water of crystalliza- 
tion. Its solution is strongly alkaline. 

A third tribasic phosphate^ often called super-phosphate 
or biphosphate, NaOv2HO,PO-H-2HO, may be obtained 
by adding phosphoric acid to the ordinary phosphate, until 
it ceases to precipitate chlorid of barium, and exposing the 
concentrated solution to cold. The crystals are prismatic, 
very soluble, and have an acid reaction. When strongly 
heated, the salt becomes changed into monobasic phosphate 
of soda. 

^ 534. Micro-cosmic Salt, or Phosphate of Soda arid Ammo- 
nia^ (H0,NH4O,NaO,PO.-fSH0,) is much used in blow- 
pipe operations as a flux. It is formed by dissolving with 
a gentle heat, 1 part of chlorid of ammonium and 6 or 7 
parts of phosphate of soda, in 2 of water. Chlorid of sodium 
is formed, and the microcosmic salt crystallizes out in rhom- 
bic prisms, which lose 8H0 by heat. 

^ 535. Bihasic Phosphate of Soda, Pyrophosphate of Soda, 
2NaO, PO3 4-lOHO. — Prepared by strongly heating com- 
mon phosphate of soda, dissolving the residue in water, and 
recrystallizing. The crystals are very brilliant, permanent 
in the air, and less soluble than the original phosphate ; 
their solution is alkaline. A bibasic phosphate, containing 
an equivalent of basic water, has been obtained ; it does 
not, however, crystallize. 

§ 536. Monobasic Phosphate cf Soda, Metaphosphate of 
Soda, NaO, PO,. — Obtained by heating either the acid tri- 
basic phosphate, or microcosmic salt. It is a transparent, 

Give the composition and properties of common phosphate of soda. 
"What is the composition of the subphosphate ? What that of the third 
tribasie phosphate? When heated, this salt becomes what? §534. 
What is the microcosmic salt 1 How is it formed ? § 535. How is bibas- 
ic phosphate formed ? What is its formula ? § o36. What is the com« 
position of the monobasic phosphate of soda ? 



304 METALLIC ELEMENTS. 

glassy substance, fusible at a dull red-heat, deliquescent, 
and very soluble in water. It refuses to crystallizej and 
dries up in a gum-like mass. 

The tribasic phosphates give a bright yellow precipitate 
with a solution of nitrate of silver ; the bibasic and raonobasic 
phosphates afford white precipitates with the same sub- 
stances. The salts of the two latter classes, fused with 
excess of carbonate of soda, yield the tribasic modification 
of the acid. — {Fownes.) 

§ 537. Borax; Bihorate of Soda ; NaO, 2BO3 + IOHO.— 
Borax crystallizes in right rhomboidal prisms, which are solu- 
ble in 15 or 1 6 parts of water ; the solution has an alkaline re- 
action and sweetish alkaline taste. It loses lOHObyheat, 
and is then very fusible, being much used in metallurgic 
processes and as a blowpipe reagent. It is entirely pro- 
cured from natural sources of boracic acid already mentioned, 
(§ 366,) and others similar in Tartary and Thibet. 

Manufacture of Glass. 

^ 538. Silicates of Soda. — Both soda and potash form 
compounds with silicic acid (§ 360) by fusion, which are 
silicates, but of uncertain composition. If 4 parts of the 
alkali be used to 1 of the silica, the glass is soluble, but 
whatever may be the proportions used, the resulting silicate 
is always an uncrystalline, homogeneous, transparent mass. 
The " soluble glass'' formed by fusing together 8 parts of car- 
bonate of soda (or 10 of carbonate of potash) with 15 parts of 
pure sand and 1 of charcoal, is insoluble in cold, but dissolves 
in 4 or 5 parts of hot water, forming a sort of varnish, which 
may be applied to wood or manufactured stuffs, which are 
to a good degree protected by it from the action of fire. 

^ 539. Glass is- a variable compound of the silicates of 
potash, soda, lime, and alumina, wdth oxyds of lead and iron, 
fused together by a very high and long-continued heat, in 
proportions suited to the object for which the glass is to be 
usad. This is not the place to describe the varied and in- 
teresting manipulations by which the fused material is blown, 
cast, moulded, or pressed into the countless forms of utility 
and ornament, which the wants of society demand. A visit 

What are the reactions of the phosphates of soda with tests? § 537. 
Give the composition of borax. What is its use ? § 538. What is said of 
the. silicates of soda ? What is the soluble glass ? § 539. What is glass ? 



AMMONIUM W$ 

to a large glass-house is always full o[ ms-tmctkn and pleas- 
ure. 

§ 540. Window-glass is a silicate of soda and lime, which 
requires an intense heat to fuse it, and forms a very hard 
and brilliant glass. Plate glass, such as is used for mirrors, 
crown glass employed for glazing, and the beautiful Bohe- 
mian glass, are all silicates of potash and lime. 

Crystal glass IS formed by fusing together 120 parts of fine 
sand, 40 purified potash, 36 of litharge or minium, (ox.yd 
of lead,) and 12 of nitre. This forms a very fusible glass, 
easily worked, and so soft as to be cut and polished, with 
comparative ease. 

Green bottle glass is usually a silicate of alumina, with 
oxyds of iron and magnesia, and potash or soda. It is formed 
of the cheapest refuse of the soap-boilers' waste and lime 
which has been used to make caustic potash or soda. 

All glass must be carefully annealed or slowly cooled 
after it is fashioned, or it will break in pieces with the least 
scratch or jar. Slow cooling of heated glass for many hours, 
or even days, for heavy articles,, renders the mass homoge* 
neous and less brittle, 

III. AMMONIUM. 

Equivalent, 18'06. Symbol, HN^, (hypothetical.) 

§ 541. The production of the ammoniacal amalgam has 
already been explained, (§ 444,) and the supposed metal 
stated to be the base of the ammoniacal salts. A more sim- 
ple mode of forming this amalgam, consists in making a 
little potassium or sodium combine by h«at in a test- 
tube, with about 100 times its weight of metallic mercury. 
This alloy, when placed in a strong solution of sal-ammoniac, 
begins at once to increase in volume by the formation of the 
ammoniacal amalgam, until it has attained very many times 
its original bulk, and has a pasty, butyraceous consistence. 

When the alloy of potassium is placed in hydrochloric acid, 
the alkaline metal decomposes the acid, forming chlorid of 



§ 540. Wliat is window and plate glass ? What is ciystal glass? Bot- 
tle glass ? What treatment does all glass require to make it fit for nse? 
§ 541. What more simple mode of forming the ammoniacal amalgam is 
here described? How does the alloy of mercury and potassium act 
in hydrochloric acid ? 

26* 



306 METALLIC ELEMENTS. 

potassium and evolving hydrogen. If we substitute for the 
acid (chlorid of hydrogen) a solution of chlorid of zinc, 
ZnCl, a like decomposition ensues ; but the zinc, instead 
of being set free like the hydrogen, combines with mercury to 
form an amalgam. The present reaction is precisely similar 
to this, chlorid of ammonium, NH^ CI, being substituted for the 
chlorid of zinc ; the ammonium which is liberated, combines 
with the mercury and forms the light pasty amalgam. It crys- 
tallizes in cubes at 32°, whereas pure mercury is fluid 
even at a temperature of — 39^ F. It is evident that it 
has combined with something which has given it new prop- 
erties. This is supposed to be the metallic radical ammo- 
niiun. It is one of the most remarkable facts in chemistry, 
that a compound of nitrogen and hydrogen should comport 
itself like a metal. 

Salts of Ammonium. 

§542. Chlorid of Ammonium ; Sal Ammoniac, l^Yi^Cl. — 
This salt occurs in nature, sometimes quite pure, as at 
Deception Island, and in volcanic districts generally. For- 
merly, the camel's dung of Egypt furnished sal ammoniac 
by sublimation from the soot of the burnt dung. It is also 
obtained largely from the ammoniacal waters of the gas-works. 
It is purified by evaporating the crude solutions to dryness, 
after treating them with a slight excess of hydrochloric 
acid to neutralize the free ammonia, and subliming the dry 
mass in iron vessels. 

It has a sharp saline taste, corrodes metals powerfully, 
is soluble in three parts of cold water, and crystallizes 
from its solution in octahedrons. The sublimed salt has a 
fibrous texture, and is very tough and difficult to pulverize. 

The formation of this compound is easily shown by using 
the apparatus already figured, (§ 434,) with hydrochloric 
acid in one flask and strong ammonia water in the other ; 
the commingling of the dry gases, driven over by heat to the 
central bottle, fills it with a white cloud of sal ammoniac, 
C1H + NH3=C1NH,. 

Hov7 if we substitute chlorid of zinc for the acid? What amalgam is 
then formed? Explain this interesting reaction. How is the amalgam of 
ammonium and mercmy different from pure mercur}^ ? What is said to 
be a remarkable fact ? § 542. How is sal-ammoniac found in nature, and 
how formed artificially? What are its properties? How is its formation 
illustrated in the class-room ? Give the reaction. 



AMMONIUM. 



307 



^ 543. Sulphuret of Ammonium and Hydrogen, {hydro- 
sulphuret of ammonia,) NH^S + HS.— This very useful 
compound is formed by passing a long-continued, slow cur- 
rent of sulphureted hydrogen from the gas-bottle (a) 
through the bot- 
tles d, e,f g, fill- 
ed with strong 
water of ammo- 
This 



nia. 



ar- 




rangement IS a 
simple form of 
Woulfe's bottles, 
(§441.) A sin- 
gle bottle of am- 
monia (as d) is 
sufficient for all common purposes. It should be kept cold. 
The ammonia absorbs an enormous quantity of the gas, its 
alkaline qualities are neutralized, and the resulting sulphuret, 
which has the strong odor of the gas, is colorless at first, 
but gradually assumes a honey-yellow. It is an invaluable 
reagent as a precipitant of the metals, and is also used in 
medicine. 

There are several simple sulphurets of ammonium, but 
they are of no particular interest. 

§ 544. Sulphate of Ammonia, or Sulphate of Oxyd of Am- 
monium, NH^O, SO 3 + HO. — This salt, which is a powerful 
fertilizer, may be procured in the large way by neutralizing 
the ammoniacal liquor of the gas-works by sulphuric acid ; 
or it may be easily obtained pure by neutralizing dilute sul- 
phuric acid with carbonate of ammonia. 

§ 545. Carbonates of Ammonia. — There are several of 
these salts. The common white sal-volatile of the shops, 
with a pungent smell and alkaline reaction, is nearly a ses- 
quicarbonate, (2NH40,3 CO^.) Exposed to the air, this salt 
becomes a white inodorous powder, which is a bicarbon- 
ate. The sesquicarbonate is a very valuable salt to the 
chemist, and also forms the basis of the smelling bottles 
so much in use. The dry white powder formed by the con- 



§ 543. How is sulphuret of ammonium formed? What is its compo- 
sition ? What its properties and uses ? § 544. What is the composi- 
tion of sulphate of ammonia ? § 545. What carbonates of ammonia are 
named ? What is the sal- volatile ? 



308 METALLIC ELEMENTS. 

tact of dry carbonic acid and ammonia in an apparatus like 
that before used, (^ 434,) is a neutral anhydrous carbonate, 
(NH3, COg,) very pungent, volatile, and dissolving readily in 
water. 

§ 546. Nitrate of Ammonia, or Nitrate of Oxyd of Ammo- 
nium, (NH4O, NO 3.) — This salt has already been noticed 
(§ 303) under the description of * laughing-gas.' Its crystals 
resemble nitre, deliquesce in moist air, and dissolve in 2 parts 
of cold w^ater, the solution sinking the thermometer to zero, 
(§ 111.) It deflagrates on burning coals like nitre. 

§ 547. All the ammoniacal salts are volatilized by a high 
temperature, yield the ammoniacal odor by trituration vi^ith 
caustic potassa or lime, and evolve the same when boiled 
with solutions of potash. They are all soluble, and give 
an insoluble, yellow, crystalline precipitate with chloride of 
platinum. 

IV. LITHIUM. 

Equivalent, 6-43. Symbol, L. 

\ 548. This very rare metal is a constituent of several 
minerals, as spodumene, petalite, lithia-mica, &c., from 
whose decomposition by a particular process, hydrate of 
lithia is obtained, the electrolysis of which afforded Davy a 
white oxydizable metal analogous to sodium. Its atomic 
number is far below that of any other metal, and only carbon 
and hydrogen are lower in the scale of equivalents ; this 
gives its oxyd a very high power of saturating acids. 

The oxyd (LO) is an alkali, but much less soluble than 
potash and soda. Its sulphate is a beautiful salt, and gives a 
rosy flame to alcohol. The lithia compounds all give this 
tint to the outer flame of the blowpipe. Its name is from 
lithos, a stone, in allusion to the natural origin of this alkali. 



What is the inodorous salt? § 546. Describe the nitrate of ammonia. 
How does its solution affect the thermometer? §547. How are the am- 
moniacal salts characterized ? § 548. What is the equivalent of lithium? 
In what minerals is it found? How is its oxyd characterized? W^hat 
common character have all the lithia compounds ? 



BARIUM. 309 

CLASS II. METALS OF THE ALKALINE EARTHS. 

I. BARIUM. 

Equivalent, 68-55. Symbol, Ba. 

§ 549. Barium is a silver-white malleable metal, which is 
easily oxydized, and melts below a red heat. It was pro- 
cured by Davy by a process similar to that which yielded 
potassium, &c. It is better obtained by passing vapor of 
potassium over baryta (oxyd of barium) heated to redness 
in an iron tube. Mercury dissolves out the reduced metal, 
and the amalgam is then distilled. 

§ 550. Baryta, or Protoxyd of Barium, BaO, — Baryta is 
best obtained by decomposing the nitrate at a high heat. 
It is a dry, white powder, which combines with water to 
form a hydrate, slaking with the evolution of great heat and 
even light. The hydrate dissolves in two parts of hot water, 
or twenty of cold, and crystallizes in flat tables. The 
aqueous solution is a valuable reagent. 

Sulphate of baryta, or heavy spar, is found abundantly as 
an associate of other minerals in veins ; and from it, or the 
native carbonate of baryta, all the artificial compounds of 
barium are formed. 

§ 551. The peroxyd of Barium, BaOg, is formed by pass- 
ing pure oxygen gas over the oxyd heated to redness in a 
porcelain tube. It is chiefly interesting as being the means 
of procuring the peroxyd of hydrogen, (§ 489.) 

Chlorid of Barium, BaCl + 2H0. — This salt occurs in 
white tabular crystals, containing two equivalents of water 
which heat will expel. It dissolves in a little more than 
twice its weight of cold water, and the solution is a valu- 
able reagent for detecting the presence of sulphuric acid, 
of which even the smallest traces are thrown down by 
all the soluble salts of baryta, as the insoluble sulphate of 
baryta. 

§552. The nitrate of baryta (BaO, NO^O) is also a 
soluble white salt, which crystallizes in anhydrous octahe- 

§ 549. What is barium? How obtained? § 550. From what sub- 
stances are the barium salts formed ? Characterize baryta and its ac- 
tion with water. § 551. How is peroxyd of barium formed, and for 
what used ? Give the characters of the chlorid of barium. For what 
is it a test ? 



310 METALLIC ELEMENTS. 

drons, and dissolves in eight parts of cold or three parts of 
hot water. Both it and the chlorid are prepared by dissolving 
the native or artificial carbonate in the proper acid. 

Sulphate of baryta — Heavy spar, (BaO, SO3,) is a mineral 
found abundantly in many places in this country, as at 
Cheshire, Ct. It crystallizes in tabular modifications of 
the rhombic prism, often very beautiful. It is also found 
massive at Pillar Point, in N. Y. Its high specific gravity 
(4*3 to 4'7) gives it the name of heavy spar. It is quite 
insoluble in water or acids, and not easily decomposed. 
When strongly heated with charcoal dust, however, it suf- 
fers decomposition, (BaO, S03 + 4Cr=:BaS + 4CO.) Car- 
bonic oxyd is given off, and the soluble sulphuret of barium 
is dissolved out from the coaly mass. 

Sulphate 0^ baryta is extensively ground up as a pig- 
ment, being mixed with white lead as an adulteration. 

The formation of sulphuret of barium has just been ex- 
plained. Higher sulphurets are formed by boiling this com- 
pound with sulphur. It is decomposed by the action of the 
air, carbonate of baryta being formed. 

\ 553. Carbonate of baryta^ BaO, COg, or the witherite of 
mineralogists, is a mineral of some interest, and useful as the 
chief source of the various compounds of baryta. All the 
soluble baryta salts are poisonous, and their presence may 
always be detected by sulphuric acid, with which they form 
an insoluble sulphate, 

II. STRONTIUM. 

Equivalent, 43.78. Symbol, Sr. 
§ 554. Strontium is obtained from its oxyd in the same 
manner as barium, and like it is a very white metal, oxydized 
easily in air, and decomposing water at common temper- 
atures. There are two oxyds, the protoxyd and the peroxyd 
of strontium, similar in properties to the like oxyds of barium. 
The sulphate of strontia, (celestine,) is a rather abundant 
mineral, and the carbonate (strontianite) is much esteemed 



§ 552. How is the nitrate of baryta characterized ? How is heavy 
spar found in nature? Give its formula and properties. §553. What 
is carbonate of baryta ? What character have the soluble salts of bar}^a? 
How is their presence detected? § 554. How is strontium obtained and 
how characterized ? What familiar salts of this metal are found native ? 



CALCIUM. 311 

by mineralogists. They are very similar in properties to 
the sulphate and carbonate of baryta. 

^ 555. The chloridof strontium (SrCl+9H0) is a deli- 
quescent salt, soluble in two parts of cold water. It loses 
its water of crystallization by heat. Both it and the nitrate 
of strontia (SrO, NO^) are much employed by pyrotech- 
nists in forming the red fire of theatres and fire-works. 
All the compounds of strontium give a peculiar red tint 
to the flame of the blowpipe, while the barytic salts do not. 
The salts of strontia are not poisonous. 

III. CALCIUM. 

Equivalent, 20. Symbol, Ca. 

§ 556. Calcium is a yellowish white metal, (Hare,) ob- 
tained like barium, and has so strong a disposition to com- 
bine with oxygen that it is difficult to observe its properties. 
Its oxyd is lime, 

^ 557. Protoxyd of Calcium — Lime, CaO. — This most 
valuable substance, so well known as quick lime, is procured 
in a state of great purity by heating the stalactites from 
Scoharie Cave, N. Y., or Wier's Cave, Ya., in a close 
crucible for some hours. The carbonic acid and organic 
coloring matters are driven olF, and pure white oxyd of cal- 
cium remains. This is an infusible, rather hard body, hav- 
ing a great affinity for carbonic acid and for water, with 
which it combines to form a hydrate, evolving great heat. 
The preparation of common mortar used in building illustrates 
this fact on a grand scale. The dry hydrate is a bulky pow- 
der, having one equivalent of water, which may be again ex- 
pelled by heat. It is soluble in about 500 parts of cold, 
and less so in hot water. The solution {lime water) is a 
very valuable reagent to the chemist, and is also used as an 
antacid in medicine. Exposure to air decomposes it, form- 
ing the carbonate of lime. The solution has a strong, dis- 
agreeable alkaline taste, and changes vegetable colors. 

Common lime is prepared by heating limestone (carbon- 



§ 655. Describe the chlorid of strontium. What is it used for? 
§ 556. What is calcium and how is it obtained? What is its# oxyd? 
§ 557. How is quick-lime prepared ? Give its properties. How does it 
act with water ? How much water dissolves it ? What is tlie solution 
used for ? How is common lime prepared ? 



313 METALLIC ELEMENTS. 

ate of lime,) in large stone furnaces, filled from the top with 
the limestone and fuel ; the fire is kept up constantly, by 
renewed charges of the materials at top, while the prepared 
caustic lime is drawn out at the bottom. 

§ 558. Mortar acts as a cement by the slow formation of 
a carbonate of lime, which binds together the grains of sand 
that make up the greater part of the mortar. The smaller 
the portion of lime used, the more firm will be the cement 
at last ; but it is then so much more diflScult to work, that 
an excess of lime is usually employed. The presence of 
oxyd of iron and manganese, of alumina, magnesia, silica, 
and other like substances, in a limestone gives the lime pre- 
pared from it the property of hardening under water, which 
is hence called hydraulic lime. 

Lime is much used in improved agriculture, as a manure. 
It acts to decompose vegetable matters, to neutralize acids, 
dissolve silica, and retain carbonic acid. It is always 
present naturally in every fertile soil, and is a constant ingre- 
dient in the ashes of most plants. 

There is a peroxyd of calcium similar to the peroxyds of 
barium and strontium. 

§ 559. Chlorid of Calcium, CaCl. — The solution of lime 
or its carbonate in hydrochloric acid to saturation, gives 
us this salt. It is usually obtained by evaporating the solu- 
tion to dryness, and fusing the dry mass in a crucible. It is 
then a white crystalline solid, with a great avidity for 
moisture, and for this reason it is used in the desicca- 
tion of gases, &c. It is soluble in alcohol, with which it 
forms a definite crystallizable compound. It also crystallizes 
from a watery solution, its crystals being used to forma very 
powerful freezing mixture with ice, (§ 111.) 

The sulphurets and phosphurets of calcium have little in- 
terest. The phosphuret being decomposed by water, is an 
available source of the spontaneously inflammable phosphu- 
reted hydrogen. 

^ 560. Sulphate of Lime — Gypsum — Sclenite, CaO, SO3. 
—This salt in the form of hydrate (CaO, SO3+2HO) is 



§ 558. What is the cause of the strength of mortar ? What is hy- 
drauHc lime ? What is said of the agricultural use of lime ? § 559. 
What is the chlorid of calcium ? For what is it used ? What is the 
phosphuret of calcium used far? § 560. Give the common names of 
sulphate of hme. 



CALCIUM. 313 

abundant in nature, and is much used in agriculture as a ma- 
nure, being ground to powder, and also after expelling the 
water by heat, as a material for stucco and plaster casts. 
It is then commonly known as * plaster of Paris.' When 
found well crystallized in transparent flexible plates, it is 
called selenite. Anhydrous gypsum also is sometimes found 
native, and is known by the mineralogical name of anhydrite. 
Gypsum is frequently associated with rock-salt. It is sol- 
uble in about 500 parts of water, and is present in most 
natural waters. By a heat of 200° to 300° it loses its 
water of composition, and when the anhydrous powder is 
moistened, the lost water is regained, and it becomes solid ; 
but if over heated, this result does not happen. 

§ 561. Fluorid of Calcium — Fluor Spar, CaF. — This is 
a rather abundant mineral, being found beautifully crystal- 
lized of various colors, in the cube and its modifications. It is 
the principal source from which we obtain the hydrofluoric 
acid, (^ 424,) by decomposition with sulphuric acid. It 
often phosphoresces very beautifully with heat, and emits 
a green, yellow, or purple light. 

§ 562. Phosphates of Lime, — There are several phos- 
phates of lime corresponding to the several phosphoric acids, 
(^ 318, § 323.) The earth of bones is a mixture of two triba- 
sic phosphates of lime, and a mineral known as apatite is also 
a phosphate of lime. The phosphates of lime are insol- 
uble in water, but dissolve in dilute acids. All cereal grains, 
and many other vegetables, contain phosphate of lime in 
their ashes. 

^563. Carbonate of Lime — Marble — Calcareous Spar, 
CaO, CO2 . — This is one of the most abundant minerals of 
the earth, forming in limestone vast mountains and wide 
spread geological deposits. It occurs most superbly crys- 
tallized iiT rhombohedral forms, which constitute brilliant or- 
naments in mineralogical collections. It is soluble in dilute 
acids, with escape of carbonic acid, and is also decomposed 
by heat, (^ 557,) leaving quick-lime. 



For what is it used? Give its properties. On what does its use in 
stucco depend? ^561. What is fluor spar? How is it found? For 
what used ? What beautiful property has it ? § 562. What plios- 
phates of lime are known ? In what do we find phosphates of lime ? 
^563. What is said of carbonate of iimc ? What otlier names has it ? 
What is formed from it'? 

27 



314 METALLIC ELEMENTS. 

^ 564. Chlorid of Lime — BleacJiing-Powders,— This val- 
uable compound is formed when chlorine gas is gradually 
admitted to hydrate of lime slightly moist and kept cool. 
The chlorine is absorbed largely, and the hleaching-powders 
of the arts are formed. It is a soft white powder, easily 
soluble in about 10 parts of water, giving a highly alkaline 
solution, which bleaches feebly. It is employed by dipping the 
goods in a weak solution of bleaching-powders, and then in 
a weak sulphuric acid water. The chlorine is thus evolved 
and does its work. Several repetitions are needed to 
complete the process. Bleaching-powders emit a strong 
smell, which is similar to chlorine, but which is due to hy- 
pochlorous acid. This compound is very useful for dis- 
infecting offensive apartments, and its energy is increased 
by the addition of a little acid. The disinfecting liquid of 
Labarraque is a compound of chlorine with soda, similar in 
composition to solution of bleaching-powders. 

The chlorid of lime is now known to be a mixture of chlo- 
rid of calcium and hypochlorite of lime, (§ 266.) 

IV. MAGNESIUM. 

Equivalent, 1 3*67. Symbol, Mg. 

§ 565. Magnesium is obtained by decomposing the chlorid 
of that metal heated to redness in a glass tube, by passing 
over it the vapor of potassium or sodium. Chlorid of potas- 
sium or sodium is formed, and the metallic magnesium is 
separated by dissolving out the soluble chlorid. 

It is a white metal, malleable and brilliant. It fuses with 
a red heat, and if heated to redness in the air, burns with a 
brilliant light, becoming oxyd of magnesium. It does not 
tarnish in the air, and does not decompose water even at 
212° ; but dissolves in acids with escape of hyd*ogen. 

^ bQQ. Oxyd of Magnesium — Calcined Magnesia, (MO.) 
— This substance is left when the carbonate of magnesia is 
heated to redness. It is a white, earthy powder, insoluble 
in water, but readily dissolves in weak acids. It occurs in 



§ 564. What are bleaching-powders? How formed ? How employed ? 
What is Labarraqne's liquor? W^hat is the known composition of 
bleaching-powders ? § ^^5. Give the equivalent and preparation of mag- 
nesium. What are its properties ? § 566. What is the oxyd of mag- 
nesium ? How is it used ? 



MAGNESIUM. 315 

nature crystallized in regular octahedrons, forming the min- 
eral periclase. It is much used in medicine as a mild and 
efficient aperient. The hydrate of magnesia (MgO, HO) 
is formed when magnesia is precipitated from its solutions 
by an alkali. Heat expels the equivalent of water. The 
hydrate is found beautifully crystallized in thin pearly plates 
at Hoboken, New Jersey. 

^ 567. Chlorid of Magnesium, (MgCl.) — This salt is best 
prepared by neutralizing equal portions of hydrochloric acid, 
one with magnesia and the other with ammonia, mixing the 
two portions and evaporating to dryness. The dry mass is 
heated in a covered crucible as long as sal ammoniac is given 
off, when pure chlorid of magnesium is left. It is a very deli- 
quescent salt, and supplies the means of procuring metallic 
magnesium. When magnesia is dissolved in hydrochloric 
acid, a hydrated chlorid of magnesium results. By heat the 
water is expelled, carrying with it hydrochloric acid, and leav- 
ing pure calcined magnesia behind. Chlorid of magnesium 
exists in sea-water. The iodid and bromid of magnesium 
are also soluble salts, but the fluorid is insoluble. 

^ 568. Sulphate of Magnesia — Epsom Salts, (MgO, 
SOg-f-THO.) — This well-known salt is easily formed by 
dissolving any of the soluble magnesian compounds in sul- 
phuric acid. It is also found native at Corydon, Illinois 
It is made on a large scale by dissolving serpentine rock in 
strong sulphuric acid. It is very soluble, and like all the 
soluble salts of magnesia, has a peculiar bitter taste. 

^ 569. The carbonate of magnesia is found native in magne- 
sian rocks, anid is also formed artificially by decomposing any 
of the soluble salts of magnesia by an alkaline carbonate. 
It is insoluble in water ; but a solution of carbonic acid 
dissolves it, and forms the celebrated Murray's solution of 
magnesia ; it is decomposed by contact of air, carbonic acid 
escapes and carbonate of magnesia is thrown down. 

Phosphate of soda with ammonia throws down a crystalline 
insoluble salt from magnesian solutions, which is the double 
phosphate of magnesia and ammonia. This is the most 
ready mode of testing for the presence of magnesia. 

How found in nature ? § 567. How is the chlorid of magnesium pre- 
pared? Describe it. When magnesia is dissolved in hydrochloric acid, 
what happens? §568. Sulphate of magnesia is how constituted ? How 
is it made in the large way? § 569. What is carbonate of magnesia? 
What is Murray's solution ? What test have we for magnesia ? 



316 METALLIC ELEMENTS. 

§ 570. Magnesia occurs abundantly in nature as a constit- 
uent of many minerals, as well as in the form of hydrate 
and carbonate. It is present in nearly all fertile soils, and 
constitutes an important part of the inorganic matters in the 
husk and seeds of many plants. The potatoe especially, 
contains a large portion of the ammonio-phosphate of mag- 
nesia, and hence bran is a useful manure for the potatoe, 
because it is also peculiarly rich in this salt. 



CLASS III. METALS OF THE EARTHS. 

I. ALUMINIUM. AL.= 13-69. 

^571. Aluminium is best obtained, like magnesium, by the 
action of sodium or potassium on its chlorid. It is a gray 
powder, not easily melted, has a metallic lustre, and burns 
when heated in the air with a bright light, forming alumina. 

§ 572. Alumina; Sesquioxyd of Aluminium; Al^Og. — 
Pure alumina is found crystallized in those precious gems, 
the oriental ruby and sapphire, which are next in hardness 
and value to the diamond. Emery is also nearly pure alu- 
mina. Alumina is an abundant ingredient in many other 
minerals, and forms a large part of many slaty rocks, from 
whose decomposition clays are produced. 

Pure alumina is a fine white powder, not rough or gritty 
like silica ; mixed with water it forms a plastic mass, 
which has all the well-known tenacious qualities of clay. 
It is the basis of the art of pottery. When alumina is pre- 
cipitated from its solutions in acids by an alkali, it falls as a 
bulky, gelatinous, transparent hydrate, which shrinks very 
much on drying, and has 3 equivalents of water of compo- 
sition at 100*^, which are expelled by heat. The anhydrous 
alumina is almost insoluble in acids, while the hydrate is 
readily dissolved, forming salts of a peculiar astringent taste, 
familiarly known in common alum. 

Alumina is precipitated as a hydrate from solution, by 
either potash, soda, or ammonia, and their carbonates ; an 

§ 570. How does magnesia occur in nature? In what plants is it 
found? § 571. How is alumina obtained? What are its properties? 
§572. What is the formula of alumina? In what is it found pure? 
What are its properties? How is its hydrate described? What differ- 
ence is there in the two forms of alumina ? How is alumina distinguish- 
ed by tests ? 



ALUMINA. 317 

excess of the two first, will redissolve the precipitate. Hy- 
drosulphuret of ammonia throws down alumina, which is true 
of none of the previously described oxyds. The chlorid of 
aluminium has no particular interest except as a means of 
procuring the metal. 

^ 573. Sulphate of Alumina, Al^OgSSOg + lSHO.— This 
salt is prepared by saturating dilute sulphuric acid with 
alumina ; it has a sweetish astringent taste, is soluble in 2 
parts of water, and crystallizes in thin plates. 

Alums. — Sulphate of alumina forms with potash, soda, 
and ammonia, double salts of much interest, called alums. 
They are all soluble salts, with a sweetish astringent taste, 
and crystallize in the regular system, or first class, (§ 219,) 
usually as modified octahedrons, which have uniformly 24 
equivalents of water of crystallization. Common potash-alum 
has the formula AUO3, 3SO3 + KO, SO3+24HO, {\ 204 ;) 
it dissolves in 18 parts of cold water, and the solution has 
an acid reaction. 

§ 574. Alum and acetate of alumina are largely employed 
in the arts of dyeing and tanning. Alumina combines with 
coloring matters, and seems to form a bond of union between 
the fibre of the cloth and the color. In this it is said to 
act the part of a w.ordant. When alum is added to the so- 
lution of a coloring matter, and the alumina is precipitated 
with an alkali, all the coloring matter is thrown down with 
it and form's what is called a lake. The common lake used 
in water-coloring is derived from madder treated in this way. 
Carmine is a lake made from cochineal. 

§ 575. Silicates of Alumina, — This is the most extensive 
and important class of the aluminous salts, and comprises a 
great number of interesting minerals. Feldspar, (AI2O3, 
3Si03-|-KO, SiOg,) which is one of the chief components 
of granite and granitic rocks, is of this class, and has 
the composition of an anhydrous alum, the sulphuric acid 
being replaced by the silicic. Kyanite and sillimanite are 
simple basic silicates of alumina. Albite is a salt having soda 
in place of the potash in feldspar, while spodumene and peta- 



§573 What is the sulphate of alumina? What are alums? Give 
the formula of common alum. § 574. In what art is alum much used? 
How does it act with colors ? What are lakes ? § 575. What is the 
most important class of alumina compounds ? Give the composition and 
properties of feldspar. 

27* 



318 METALLIC ELEMENTS. 

lite are similar compounds, with a portion of the soda repla- 
ced by lithia. Many other similarly constituted compounds 
are found among minerals, some of which are hydrous and 
others anhydrous, and varied by frequent substitution of 
peroxyd of iron, or other isomorphous bases, for the alu- 
mina. 

Pottery. 

§ 576. Pottery. — The decomposition of feldspar and 
other aluminous minerals and rocks, gives origin to the clays 
which are so important in the art of pottery. Decomposed 
feldspar forms porcelain clay, commonly called Kaolin, The 
undecomposed mineral is often ground up to mix with the 
materials for porcelain. The feldspar of Middletovvn, Ct., 
and Wilmington, Delavi^are, is used in large quantities for 
this purpose. 

The diiference between porcelain and earthen ware, con- 
sists in the partial fusion of the materials of the former 
by the heat of the furnace, which gives it the semi-trans- 
parency and great beauty for which it is so highly prized. 
The glaze in porcelain is formed of a more fusible mixture 
of the same materials put over the articles as a wash, after 
they have been once through the furnace ; (in which state 
they are called biscuit ware ;) they are then baked again 
at a heat which fuses the glaze, but which does not soften 
the body of the ware. 

^ 577. Stone ware and granite ware are coarser kinds of 
porcelain, of less fusible materials, and very strong. This 
kind of pottery, as well as much of the earthen ware, (queens 
ware, &c.,) is glazed by throwing common salt into the fur- 
nace, (§ 526.) Earthen ware is formed of every variety of 
clay, fine or coarse, according to the use and value of the 
article. Beautiful white clays are found abundantly in many 
parts of this country, as in New Jersey, Martha's Vineyard, 
Virginia, &c. Earthen ware, when not glazed by salt, is usu- 
ally dipped in a thin paste of clay and oxyd of lead, which 
forms a very fusible brilliant glazing, (silicate of lead,) but it 
is so liable to destruction by acids, that it is considered un- 

§ 576. What is the origin and composition of clays? Of what mate- 
rial is porcelain composed? How does it differ from earthen ware ? Of 
what does the glaze consist ? § 577. What are the materials of common 
earthen ware ? How is it sometimes glazed ? 



ALUMINA. 



319 



safe to be used in culinary operations where acids are em- 
ployed. Crucibles are formed from a very refractory sili- 
cious clay, being designed to resist the action of an in- 
tense heat. Bricks are a coarse kind of earthen ware, made 
from the same sort of material which is used for garden- 
pots and draining-tiles. 

§ 578. The art of pottery is a very ancient one, probably 
the most ancient of human inventions. The Chinese were 
the first who practised the art of making porcelain, and had 
been in the habit of manufacturing it for many centuries be- 
fore it was known to Europeans. Hence the origin of the 
common name china, meaning porcelain. The painting of 
porcelain is an art requiring a refined knowledge of chemis- 
try as well as of design. All the colors used in this art are 
metallic oxyds, which are put on after the ware has been 
once baked. The colors result from compounds formed by 
the metallic oxyds with alumina by fusion, and do not ap- 
pear until after the baking. Metallic gold is put on in the 
form of an oxyd, and the steel lustre is produced by metal- 
lic platinum. 

II. GLUCINUM. III. YTTRIUM. IV. ZIRCONIUM. 

V. THORIUM. VI. CERIUM. VII. LANTANUM. 

§ 579. All these metals are so rare as to be unknown 
even to most chemists. Their oxyds occur in several min- 
erals, nearly all of which are among the most uncommon 
specimens in mineralogical collections. 2. Glucina or the 
sesquioxyd of glucinum, (GgOg,) is the most abundant, 
being found to the amount of 17 per cent, in the gems beryl, 
emerald, and ^chrysoberyl. It very much resembles alumina, 
and is named in allusion to the sweet taste of its salts. 3. 
Yttria, the oxyd of yttrium, (YO,) is a white earthy powder, 
forming sweetish salts, but differing from alumina and glu- 
cina in not being redissolved like them in an excess of pot- 
ash and soda : this earth is found in the minerals yttro-cerite, 
gadolinite, and yttro-tantalite. 4. Zirconia, sesquioxyd of 
zirconium, (Zr^Og,) which is the earth of the zircon or hy- 
acinth, much resembles alumina, but differs from it and from 
glucina, yttria, and thorina, by being precipitated from its 
solutions, as an insoluble sulphate, by boiling with solution 

§ 578. How is porcelain colored? § 579. What six metals are included 
in this section? In what mineral is glucina found? Describe yttria. 
In what mineral is zircoiiia found ? What are its properties ? 



320 METALLIC ELEMENTS. 

of sulphate of potash. 5. Thorina, the oxyd of thorium, is 
found in only one or two very rare minerals, as in thorite 
and monazite ; its specific gravity is 9, being much higher 
than any other earth. 6. Cerium, and 7. Lantanum, — The 
oxyds of these two rare metals are invariably associated with 
each other, and also with that of another metal, didi/mium, 
not yet fully described ; they are found only in some very 
rare minerals, as cerite, allanite, monazite, &c. The oxyd 
of cerium forms beautiful yellow salts, while the oxyd of lan- 
tanum forms equally beautiful rosy compounds ; the latter 
has been named in allusion to its having been long concealed 
or hidden under cerium, with which it is associated. 

CLASS IV. METALS WHOSE OXYDS FOUM POWERFUL 

BASES. 

I. MANGANESE. 

Equivalent, 27 67. Symbol, Mn. Density, 8. 

\ 580. Manganese is never found as a metal in nature, but 
may be produced from its black oxyd by a high heat with 
charcoal. Metallic manganese is a gray, brittle metal, not 
magnetic, and resembles some varieties of cast iron. It 
dissolves rapidly in sulphuric acid with escape of hydrogen. 

Manganese in the form of the black oxyd is an important 
and pretty common metal. Its great use is for producing 
chlorine, (^ 259,) and in the manufacture of glass, w^here it 
acts by its oxygen to decolorize the compound, 

§ 581. The oxyds of manganese are numerous ; we give 
the formulas of six, and there are possibly one or two more, 
viz.: protoxyd, MnO ; sesquioxyd, (or braunite,) Mn2 03; 
peroxyd, or deutoxyd, (pyrolusite,) MnO^ ; red oxyd, (haus- 
mannite,) Mn3 04 ; manganic acid, MnOg ; hypermanganic 
acid, Mn^O^. 

The protoxyd is a green-colored powder, formed from 
heating the carbonate of manganese in hydrogen. It is a 
powerful base, attracts oxygen from the air, and is the base 
of the beautiful rosy-colored salts of manganese. 

What is said of thorium? With what is cerium always associated? 
§ 580. What is said of manganese ? What form of it is most common? 
For what is it used? § 581. How many and what oxyds of manganese 
are named? Which is the base of the rosy-colored salts? What is the 
sesquioxyd ? 



MANGANESE. 321 

The sesquioxyd or hraunite occurs crystallized in octahe- 
drons, and forms belonging to the dimetric system. 

The hydrated sesquioxyd (manganite) is a finely crystal- 
lized mineral in long black prisms, found in superb speci- 
mens at Ilfeld, in the Hartz. In powder the sesquioxyd is 
brown, it is decomposed by hydrochloric acid with the evo- 
lution of chlorine ; but sulphuric acid combines with it to 
form BL sesquisulphate, which yields a purple double salt 
with sulphate of potash, (manganese alum,) isomorphous 
with the corresponding salt of alumina. The salt is, how- 
ever, very easily decomposed by a gentle heat. 

§ 582. The peroxyd is the most common ore of manga-, 
nese. It is found abundantly at Bennington, Vt., and other 
places in this country. When crystallized it is called 
pyrolusite, and beautiful specimens of this mineral have been 
observed at Salisbury and Kent, Conn., among the iron ores. 
The high commercial importance of this ore renders it con- 
venient to have a ready mode of determining its value. This 
depends on the amount of peroxyd present 
in the black powder, which is often fraudu- 
lently adulterated. The pure mineral con- 
tains about 73 parts of manganese and 27 of 
oxygen, (or27.67+16r=:43'67, the combining 
number.) To test the value of any specimen, 
50 grains of it are put into a little flask like 
the annexed figure, fitted with a chlorid of calcium tube, 
to prevent the vapor of water from escaping. About half 
an ounce of water is added to it; and 100 grains of hy- 
drochloric acid placed in the little tube and slipped in ; 
50 grains of crystallized oxalic acid are now added, the 
chlorid of calcium tube fitted on, and the whole apparatus 
weighed. The hydrochloric acid is now brought in contact 
with the materials in the bottom of the flask by inclinino- the 
vessel, and heat being applied, decomposition takes place, and 
the chlorine evolved converts the oxalic acid into two equiv- 
alents of carbonic acid. Two equivalents of carbonic acid, 
represent one of chlorine, and consequently one of peroxyd 
of manganese. The equivalent of peroxyd of manganese is 
nearly 44, which is exactly the number of two equivalents 

What is the hydrated sesquioxyd ? What is said of the sulphate of 
the sesquioxyd ? § 582. Which is the most common ore of manganese ? 
Where and how is it found? How is its vakie determined? Describe 
the process and give the reaction. 




322 METALLIC ELEMENTS. 

of carbonic acid ; and consequently the loss of weight suffered 
by the flask when the operation is complete, will represent 
almost exactly the amount of peroxyd of manganese in 50 
grains of the sample.* 

^ 583. Manganic acid is known only in combination, gen- 
erally as manganate of potash, or ^ chamelion mineral,'' 
which is formed by fusing together a mixture of peroxyd of 
manganese, chlorate of potash, and caustic potash. A dark 
green mass is formed, which contains manganate of potash. 
In this case the manganese obtains oxygen from the chlorate 
of potash, and the manganic acid thus formed combines 
with potash, giving a salt in green crystals. This salt, dis- 
solved in water, gives a brilliant emerald-green solution, 
which almost immediately changes color, being in quick 
succession green, blue, purple, and finally crimson-red. 
This last color is due to the presence of permanganic acid, 
which, however, cannot be separated from its combinations, 
but forms a salt with potash in beautiful purple crystals. 
The compounds of permanganic acid are more stable than 
the manganates. The salts of these acids are respectively iso- 
morphous with sulphates and perchlorates, (SOg and CI^O^.) 

§ 584. The chlorids of manganese (MnCl and Mn2Cl3) 
correspond to the protoxyd and sesquioxyd. The chlorid is 
formed abundantly in acting on black oxyd of manganese, 
(§ 259,) with hydrochloric acid. The mixed solution of 
chlorids of iron and manganese is evaporated to dryness, 
and then heated to dull redness. The chlorid of manganese 
is then dissolved out from the dry mass, leaving the insolu- 
ble protoxyd of iron behind. It has a beautiful pink tint, and 
deposits tabular rosy-colored crystals on evaporation. It is 
soluble in alcohol, and fusible by heat. The sesquichlorid 
is formed by solution of sesquioxyd in cold hydrochloric 
acid, but is decomposed by a gentle heat and evolves chlorine. 

^585. The salts of manganese are numerous, and in a 
chemical view quite important. Sulphate of manganese 
is a very beautiful rose-colored salt, isomorphous with sul- 
phate of magnesia. It is used to give a fine brown dye to 
cloth, being decomposed by a solution of bleaching powder, 
which forms the brown peroxyd in the fibre of the stuffs. 

§ 583. Describe manganic acid and the curious salt it forms with pot- 
ash. What is the changeable compound called? What is said of the 
salts of manganic and permanganic acid ? § 584. Describe the chlorids 
of magnanese. § 585. What is said in general of the salts of manganese ? 

* Fownes, p. 275, Eng. ed. 



IRON. 



323 



II. iron: 



Equivalent, 27' 14. Symbol, Fe. Density, 7-8. 

§ 586, Iron is found malleahle, and alloyed with nickel, in 
large masses of meteoric origin. One of these, discovered in 
Texas, weighs 1635 pounds, and is now in Yale College 
Cabinet, It is not certain that malleable iron of undoubted 
terrestrial origin has yet been discovered in nature. Iron is the 
most abundant and most important metal known to man. Its 
ores are found everywhere, and often in immediate con- 
nection with the coal and limestone necessary to reduce 
them to the metallic state. There is no soil, and scarcely 
any mineral, which^ does not contain some proportion of 
the oxyd of iron. 

§ 587. Pure iron is difficult to prepare. The purest iron 
of commerce is always contaminated with a portion of sili- 
con and carbon. When quite pure it is nearly white, 
quite soft, perfectly malleable, and the most tenacious of all 
metals. Its density is 7*8, which may be a little increased 
by hammering. It crystallizes in the first class, as is 
beautifully shown in the crystalline 
structure of the meteoric iron. It 
fuses with extreme difficulty, first 
becoming soft or pasty, in which 
state it is welded. When intensely 
heated in air or oxygen gas it com- 
bines with oxygen, burning with 
brilliant light and numerous scin- 
tillations, and is converted into oxyd 
of iron, (254.) Iron also attracts 
oxygen at common temperatures, 
forming rust. This does not hap- 
pen in dry air, but the presence of 
moisture, and particularly of a little acid vapor, very much 
promotes its formation. Iron decomposes water very rapidly 
at a red heat, hydrogen being evolved. It is the chief me- 
dium of magnetism, being powerfully attracted by the magnet, 
and also itself susceptible of this influence. 




§ 586. What is the equivalent of iron ? How is malleable iron found ? 
What is said of its abundance and value ? § 587. Give the properties of 
iron. What is said of its fusion and welding ? How does it behave with 
oxygen ? 



324 



METALLIC ELEMENTS. 



§ 588. Two States of iron are known, an active and 3. pas- 
sive state. The first is its ordinary condition. It assumes 
the second state when in contact with platinum in strong nitric 
acid; the platinum being withdrawn, the iron remains inert and 
unaffected, even by this powerful acid, and then refuses to 
precipitate copper or manifest any of its ordinary chemical 
properties. 

^ 589. The chief ores of iron are, (1,) brown hematite or 
hydrous peroxyd^ from which the best iron is made. (2.) 
The red hematite and specular iron or peroxyd. (3.) Clay iron 
stone, which is an impure carbonate of iron, or carbonate 
of iron with carbonate of lime and magnesia. This is the 
nodular ore of the coal formations. (4.) Black or magnetic 
oxyd of iron, which is the ore of the iron mountains of 
Missouri and of Sweden. 

^ 590. The reduction of the ores of iron to the metallic 
state is performed in large furnaces called high or blast 

furnaces. These are built of 
stone, in a conical form, 30 to 
50 feet high, and lined inter- 
nally with the most refractory 
fire-bricks. The furnace is 
divided into the throat, the 
fire-room, {b,) the boshes, (e,) 
(that portion sloping inward,) 
the crucible, (/,) and the hearth, 
(A.) The blast of air — supplied 
from very large blowing cylin- 
ders—is introduced by two or 
three tuyere pipes [aa) near 
the bottom. In the most im- 
proved furnaces, the air-blast is 
heated intensely by causing it 
_ to pass through a series of 
pipes in the upper portion of the furnace, so as to have a 
temperature of 500° or more when it enters the furnace. 
When the furnace is brought into action, it is first heated 
with coal only, for about 24 hours ; and then is charged 
alternately with proper proportions of coal, roasted ore, and 




§ 588. What two states of iron are mentioned ? How is the passive 
state induced? §589. What ores of iron are enumerated? §590. 
How is the reduction of iron effected? Describe the high furnace. 



IRON. 325 

flux, until it is quite full. When once brought into action, 
the blast is kept up for months or even years, until the furnace 
requires repairing. The ore is reduced on the boshes, and 
in the upper part of the crucible, and the melted metal col- 
lects on the hearth, covered by the moUen flux. From time 
to time, the iron is drawn off by an opening previously stop- 
ped with clay, and run into rude open moulds in sand. This 
is cast iron, and is of various qualities, according to the 
character of the ore, and the working of the furnace. If 
malleable bar iron is wanted, the cast-iron is again melted, 
in what is called the puddling furnace, where it is stirred 
about by an iron rod, in contact with oxyd of iron, and a 
current of heated carbonic oxyd from the high furnace. It 
gradually becomes stifl* and pasty from the burning out of the 
carbon, and from some molecular change not well understood. 
It is finally raised in a rude ball and placed under the blows of 
a huge tilt-hammer, when the scoria is pressed out and the 
particles made to cohere. It grows tenacious by a repetition 
of this process, being cut up and piled or faggoted and re- 
heated several times, until it is finally made into tough and 
fibrous metal. 

^591. Steel is formed from refined iron by heating in con- 
tact with charcoal in close vessels, (called cementation.) It 
gains from one to two per cent, of carbon, becomes fusible, 
and can be tempered according to the use for which it is 
designed. 

^ 592. The oxyds of iron are four, viz: (1,) protoxyd, 
(FO ;) (2,) sesquioxyd, commonly called peroxyd, (FCgOg ;) 
(3,) black oxyd, (magnetic oxyd,) (FCgjO^,) and (4) ferric 
acid, (FeOg.) 

The protoxyd of iron is a powerful base which is un- 
known in nature except in combination. It saturates acids 
completely and is isomorphous with a large class of bodies, 
of which zinc and magnesia are examples, (§ 231.) This 
oxyd is thrown down from its solutions by potash, as a 
whitish bulky hydrate, that soon gains another dose of oxygen 
from the air becoming brown, and finally red. Its salts when 
soluble have a styptic taste (like ink) and a greenish color. 

§ 592. The peroxyd of iron is found native in the beauti- 



What is the hot blast? What is the operation of the furnace ? "What 
is cast iron? How is malleable iron made from cast iron? § 591. What 
is steel ? § 592. What are the oxyds of iron ? Give their formulas. 

28 



326 METALLIC ELEMENTS. 

ful specular iron of Elba, and also in the red and brown 
hematites. It is slightly acted on by the magnet, and after igni- 
tion is almost insoluble in strong acids. It is isomorphous 
with alumina, and is generally associated with it in soils and 
many minerals. It is often of a brilliant red, and as ochre of 
various tints, is much used as a pigment. Ammonia precip- 
itates it from its solutions as a bulky red hydrate. 

§ 594. Black oxyd of iron is familarly known in the com- 
mon magnetic iron ore and native lode-stone. It crystal- 
lizes in octahedrons. It forms no salts. The finery cinders 
or scales thrown off under the smith's hammer are this 
oxyd. 

Ferric acid is a new compound, corresponding to man- 
ganic acid, discovered by M. Fremy. It is formed as a 
ferrate of potash, when one part peroxyd of iron and 4 parts 
of nitre are heated to full redness in a covered crucible for 
an hour. The ferrate of potash is dissolved out of the porous 
mass by ice-cold water. The solution has a deep ame- 
thystine color, and is easily decomposed by heat. A soluble 
salt of baryta precipitates ferric acid as a beautiful rosy red 
ferrate of baryta, which is permanent. 

The chlorids of iron (FeCl and Fe2Cl3) correspond to the 
protoxyd and sesquioxyd (peroxyd) of the same base. The 
latter is often used in medicine and may be formed by sat- 
urating hydrochloric acid with freshly prepared peroxyd of 
iron. The protiodid of iron is also a valuable medicine. 

^ 595. The sulphurets of iron are found native, and are 
well known as pyrites. The protosulphuret is easily formed 
artificially, by fusing sulphur with iron-filings ; they ignite 
with a vivid combustion, (§ 460,) and protosulphuret of iron 
is formed, which is much used in preparing sulphureted 
hydrogen. Yellow iron pyrites and white iron pyrites are 
dimorphous forms of the bisulphuret, (FeS^ ;) the first is one 
of the most common of crystallized minerals. The mag- 
netic sulphuret, magnetic pyrites, corresponds in composition 
to the magnetic oxyd. 

^ 596. Of the salts of iron, the green vitriol or protosulphate 
(FeO, SO3 + 7HO) is the most important. It is made in 
immense quantities, as at Stafford, Vt., from the decompo- 

Describe the protox)^d. § 593. How is the peroxyd known? § 594. 
What is the black oxyd? What is ferric acid? What chlorids of iron 
are named ? What oxyds do they correspond to ? § 595. What are the 
sulphurets of iron? For what is the protosulphuret used? What is the 
name of the ordinary sulphuret? 



CHROMIUM. 327 

sition of iron pyrites, which furnishes both the acid and the 
base. This salt crystallizes beautifully, and is much used 
as the basis of all black dyes and ink, and in the manufac- 
ture of Prussian blue. It is called copperas in the arts. 
Persulphate of iron is a sulphate of the peroxyd, (Fe^ 
O3 + 3SO3. Carbonate of iron occurs in nature as spathic 
iron ore, which is isomorphous with carbonate of lime. A 
variety of steel is made directly from this ore without ce- 
mentation, ( ^ 591.) It is formed artificially by precipita- 
ting a solution of sulphate by an alkaline carbonate, and is 
used in medicine. The chlorids, iodids, and nitrates of iron 
are all easily formed from their appropriate acid and oxyds. 
The presence of a salt of iron is easily detected by the 
fine blue (prussian blue) formed on adding prussiate of 
potash to the solution ; and an infusion of galls gives a black 
color (ink) to solutions of iron. 

III. CHROMIUM. 

Equivalent, 28 '14, Symbol, Cr. Density, 6. 

§ 597. Chromium in combination with iron is rather an 
abundant substance, particularly in this country, being found 
as chromic iron at Barehills, near Baltimore, and in other 
places. The beautiful red chromate of lead is also a natu- 
ral product in Siberia. The metal, from its great affinity for 
oxygen, is very difficult to procure. It is a hard, almost in- 
fusible substance, resembling cast-iron, nearly insoluble in 
acids, and does not decompose water. It may be oxydized by 
fusion with'uitre, but does not change in the air. 

^ 598. Chromium forms five coinpounds with oxygen ; of 
which the sesquioxyd (Cr^Og) and chromic acid (CrOg) are 
the most important. Chromium bears the strongest analogy 
in its chemical character to manganese and iron. The per- 
fect identity of constitution in the oxyds of these three 
metals is shown in the following tabular arrangement : 

Acids. 

Protoxyd. Sesquioxyd. Black oxyd. / "^ % 

Manganese forms, MnO MnoOg Mn304 MnOg MnaOY- 
Iron forms, FeO FcoOs re304 FeOg 

Chromium forms, CrO CraOa Cr304 CrOs OroO-;. 

§ 596. Which of the salts of iron is named as very important? How 
and where is it made in this country ? What is the carbonate and for 
what used? § 597. Give the equivalent and symbol of chromium. How 
is it found associated ? What of the metal ? § 598. What compounds 
does c hromium form with oxygen] 



328 



METALLIC ELEMENTS. 



The protoxt/d of chromium has only very lately been form- 
ed by M. Peligot, and is a strong base. It acts in combi- 
nation like the protoxyd of iron, with which it is isomorphous. 

^ 599. The sesquioxyd of chromium is easily prepared, by 
treating a boiling and rather dilute solution of bichromate of 
potash, with an excess of hydrochloric acid, 'and then with 
small successive portions of alcohol or sugar, until it assumes 
a fine emerald green tint. Ammonia in slight excess will 
now throw down the hydrated oxyd as a bulky pale green 
precipitate, soluble in acids. When this precipitate is dried, 
it shrinks very much, and on ignition suddenly undergoes 
a vivid incandescence and becomes deep green. The ses- 
quioxyd of chromium is a feeble base like those of iron and 
alumina, and may replace them in combination, as in the form- 
ation of -chrome alum with sulphate of potash. All the salt 
of this oxyd are either emerald green or bluish purple. It 
imparts a rich tint of green to glass and porcelain, and is 
the cause of the high color of the emerald. 

The protochlorid of chromium (CrCl) is obtained as a white 
and very soluble substance by the action of dry hydrogen 
gas on the following compound. The sesquichlorid (Cr^ 
CI 3) is prepared by passing chlorine gas over an ignited 
mixture of the sesquioxyd and charcoal. It forms a crystal- 
line sublimate of a peach-blossom color, and is insoluble in 
water. The sesquioxyd dissolves in hydrocloric acid, but 
the hydrated chlorid thus obtained is decomposed by heat. 

§ 600. Chromic acid (CrOg) is readily formed by treating 
a cold and concentrated solution of bichromate of potash with 
one and a half parts of sulphuric acid. The mixture when 
cold deposits brilliant ruby-red prisms of chromic acid. The 
sulphate of potash in solution above, may be turned off; and 
the chromic acid dried on a porous brick, being carefully 
covered with a glass to prevent access of organic matters, 
which at once decompose it. If a little of this acid be 
thrown into alcohol or ether, the violence of the action is 
such as to set fire to the mixture. Chromic acid forms nu- 
merous salts, which are all highly colored. 

§ 601. The chr ornate of potash and also the bichromate are 



With what metals is it closely allied? How is this relation shown? 
Give the comparative formnlas of the oxyds of manganese, iron, and 
chromium. What is said of the protoxyd? § 599. How is the ses- 
quioxyd prepared ? What are its properties and analogies ? § 600. How 
is chromic acid prepared ? What are its properties ? Describe the chlo- 
rids of chromium. 



NICKEL. 329 

both familiar e^caniples. The first (KO, CrOg) is formed 
on a very large scale by decomposing the native chromic 
iron with nitrate of potash, by aid of heat. Chromate of 
potash is dissolved out from the ignited mass, and crystal- 
lizes in anhydrous yellow crystals. It is isomorphous with 
sulphate of potash, dissolves in two parts of cold water, 
and is the source of all the preparations of chromium. 

Bichromate of potash (CO, 2Cr03) is formed by adding 
sulphuric acid to a solution of the yellow chromate, when 
half the potash is removed, and the bichromate crystallizes 
by slow evaporation into brilliant red crystals of a rhombic 
form, which are soluble in ten parts of cold water. 

§ 602. Chromate of lead — chrome yellow — (PbO, CrOg,) is 
the well-known pigment prepared by precipitating the nitrate 
or acetate of lead by a solution of chromate or bichromate of 
potash. Chrome green is the oxyd of chrome, prepared in a 
particular way. 

Chloro-chromic acid (CrOg + CI) is a deep red volatile 
liquid resembling bromine, which appears when equal 
weights of common salt and bichromate of potash are 
intimately mixed, and heated in a retort with three parts of 
sulphuric acid. The chloro-chromic acid distills over, filling 
the receiver with a superb ruby-red vapor. Water decom- 
poses it, forming chromic and hydrochloric acids. 

III. NICKEL. 

Equivalent, 29*59. Symbol, Ni. 

^ 603. Nickel is rather a rare metal, but may be prepared 
from the speiss or crude nickel of commerce. It is white 
and malleable, having a density of 8 27, and fuses above 
3000°* It is not easily oxydized, and is one of the two 
or three magnetic metals ; magnets may be made of it 
nearly as powerful as those of iron. Nickel is almost always 
found alloyed in masses of meteoric iron. In this country 
it has been obtained at Chatham, Ct. as an arseniuret, and 
also at Mine la Motte, in Missouri, as an earthy oxyd asso- 
ciated with cobalt. 

§ 601. How is chromate of potash formed? Bichromate of potash is how- 
formed ? §602. What is chrome yellow? What chrome green? De- 
scribe chloro-chromic acid. § 603. In what state does nickel occur in na- 
ture ? Describe its properties. 

28» 



330 



NON-METALLIC ELEMF-NTS. 



There are two oxyds of nicM. The protoxyd (NiO) is 
prepared by precipitating a solution of nickel by caustic pot- 
ash, which gives an apple-green hydrated oxyd, that by 
heat loses its water and becomes gray. The oxyd of nickel 
is isomorphous with magnesia, and has been obtained crys- 
tallized in regular octahedrons. The salts of this oxyd have 
a fine green color, which they impart to their solutions. 

The peroxyd of nickel (Ni02, O3) is a dull black pov/der, 
and of no particular interest. 

§ 604. The sulphate of nickel (NiO, SO3 + 7H0) is a finely 
crystallized salt occurring in green prisms, which lose their 
water of crystallization by heat. It forms beautiful well 
crystallized double salts, with the sulphates of potash and 
ammonia. Oxalic acid precipitates an insoluble oxalate of 
nickel from the solution of the sulphate, and the metallic 
nickel is easily obtained from the oxalate by heat. 

Nickel is chiefly employed in making German silver, a 
white malleable alloy, composed of copper 100, zinc 60, and 
nickel 40 parts. 



IV. COBALT. 

Equivalent, 29*52. Symbol, Co. 

§ 605. Cobalt is a metal almost always associated with 
nickel, and closely resembling it in many of its reactions. 
When pure, it is a brittle reddish white metal, with a density 
of 8'53, and melting only at very high temperatures. It is 
generally said to be magnetic, but is not so when quite pure. 
It dissolves with difficulty in strong sulphuric acid, and is not 
oxydized in air. It forms two oxyds every way analogous 
to those of nickel. Its protoxyd is a grayish pink powder, 
very soluble in hydrochloric acid, and forming pink salts. 
This oxyd occurs native. 

The chlorid of cobalt (CoCl) is formed by dissolving the 
oxyd in hydrochloric acid, when chlorine escapes. The so- 
lution is pink, and when very dilute may be used as a blue 
sympathetic ink, which may be made green by mixing a 
little chlorid of nickel. Writing made by this on paper is 



What are its oxyds ? In what form does the protoxyd crystallize ? 
§ 604. Describe the sulphate and oxalate of nickel. What is the com- 
position of German silver ? § 605. What are the characters of cobalt ? 



ZINC, 331 

colorless when cold, but becomes of a fine blue or green 
when gently warmed, and loses its color again on cooling. 
The salts of cobalt and nickel are isomorphous with those 
of magnesia. They are not thrown down by sulphureted hy- 
drogen, but give blue or green precipitates with potasfi, 
soda, and their carbonates. The same precipitates with 
ammonia are soluble in excess of that reagent. Oxyd of 
cobalt imparts a splendid blue to glass, and the pulverized 
glass of this color is called smalt and potoder blue. Zaffre 
is an impure oxyd of cobalt used to give the fine blue color 
to common earthen ware. 

V. ZINC. 

Equivale7it, 33. Symbol , TaXI, Density, 6-86. 

§ 606. Zinc is an importanf and rather common metal. 
It is not found native, but a peculiar red oxyd of zinc 
abounds at Sterling, New Jersey, and calamine or carbon- 
ate of zinc is found abundantly in many places. The ores 
of zinc are reduced by heat and charcoal, in large crucibles 
closed at top, but having an iron tube descending from near 
the top, through the bottom, and terminating in a vessel of 
water. The metal being volatile, rises and escapes by the 
tube into the water. This is called distillation by descent. 

^ 607. Zinc is a bluish white metal, easily oxydized in 
the air, and crystallizes in broad foliated laminae, well seen 
in the fracture of an ingot of the commercial article. It is 
called spelter in the arts, and is used chiefly to alloy copper 
in forming brass. Zinc is not a malleable metal, at ordin-^ 
ary temperatures, but at a temperature of between 250^^ and 
300° it becomes quite malleable, and is then rolled into sheet 
zinc. At 400° it is again quite brittle, and may be granu- 
lated by blows of the hammer ; at 773° it melts, and if air 
has access to it, it takes fire, and burns rapidly with a brill- 
iant whitish green flame, giving off flakes of white oxyd of 
zinc, sometimes called lana philosophica. It is completely 
volatile at a red heat. 

The chlorid of zinc, ZnCl, is a salt easily prepared when 

What interesting experiment is mentioned with the chlorid ? With 
what metal is the oxyd of cobalt and its salts isomorphous ? What use 
is made of the oxyd of cobalt? § 606. How is zinc reduced from its 
ores? § 607. What are its properties? At what temperature is it mal- 
leable ? Is it combustible ? 



332 METALLIC ELEMENTS. 

zinc is dissolved in hydrochloric acid, hydrogen being 
evolved. 

Sulphuret of zinc, Blende, ZnS, occurs native in the forms 
of the first crystallographic class, and is colored yellow, 
brown, and black. This is one of the ores of zinc (called 
black Jack) from which the metal is obtained. 

The oxyd (ZnO) is a white powder, insoluble in water, 
but easily dissolved in all acids, forming a series of salts, of 
which the most important is — 

Sulphate of Zinc, or White Vitriol, ZnO, SOg + THO. — 
This salt has the same form as the sulphate of magnesia, and 
looks extremely like it. It dissolves in 2i parts of cold 
water, and forms double salts with the sulphates of ammo- 
nia and potash. It is a powerful emetic. 

Sulphuret of ammonium ^throws down a characteristic 
white precipitate of sulphuret of zinc from its solution. 

VI. CADMIUM. 

Equivalent, 55-74. Symbol, Cd, Density, 86. 

^ 608. Cadmium is generally found associated with zinc, 
and is almost as volatile a metal as mercury. It is quite 
malleable, white, and harder than tin. It fuses at 442°, and 
volatilizes at a temperature a little above this. It is not 
easily oxydized, and is but slightly soluble in hydrochloric 
or sulphuric acids. Nitric acid dissolves it with ease, 
forming a salt from which sulphureted hydrogen throws down 
a very characteristic orange-yellow sulphuret. This com- 
4)0und is also found native and crystallized, (greenockite.) 

VII. LEAD. 

Equivalent, 103-56. Symbol, Pb. Density, 11 •35. 

§ 609. This useful and familiar metal occurs in boundless 
profusion in this country, chiefly as galena, or sulphuret of 
lead, from which the metal is easily obtained by smelting the 
ore with a limited amount of fuel, at a low heat. The car- 
bonate, phosphate, chromate, and arseniate, are also natural 



Describe the sulphuret. What is said of the sulphate ? § 608. What 
are the properties of cadmium ? Describe its sulphuret § 609. What 
is the chief ore of lead ? 



LEAD. 333 

salts of lead mucli prized by the mineralogist. Lead is a blu- 
ish gray metal, very soft and ductile, but not very tenacious ; 
it oxydizes in the air quite rapidly, forming a coat of oxyd, 
or carbonate, which protects it from further corrosion. Its 
density is 11*35, and it fuses at 612° ; when melted it com- 
bines rapidly with oxygen from the air, forming either prot- 
oxyd, or red oxyd, according to the heat. 

Lead is slowly acted upon by soft or rain water, and also in 
some cases by hard water ; so that it is unsafe to use water- 
pipes of lead, unless it has been proved by experiment that 
the particular water in question does not act on this metal. 
It is a deadly poison, at least in the form of carbonate, which 
is always formed under these circumstances. 

Lead does not easily dissolve in dilute acids, except in 
nitric, with which it forms a soluble salt : strong sulphuric 
acid dissolves it when heated, forming the nearly insoluble 
sulphate of lead. 

There are three oxyds of lead, of which only the prot- 
oxyd has basic properties. 

§ 610. Protoxyd of Lead ; Lilharge, PbO. — This oxyd is 
a yellow powder, formed by slowly oxydizing lead, with 
heat. It is slightly soluble in water, and the solution is al- 
kaline. It fuses easily, and then dissolves silica with great 
rapidity ; hence its use in glazing pottery (§ 577) and in the 
manufacture of glass, (§ 540.) It forms a large class of 
definite salts, which have often a sweet taste, as, for example, 
the acetate or sugar of lead. The sesquioxyd has the for- 
mula Pb^Og, and is a reddish-yellow insoluble powder. 

The peroxyd, Pb Og, is prepared by acting on the red lead 
with nitric acid ; it is a puce colored body which acts the 
part of an acid, with bases forming salts. 

^611. Red Oxyd^or Red Lead, Pbg O4. — This is a common 
pigment, and is formed when melted lead is exposed to a 
temperature of 600° or 700°. It is of variable constitution, 
according to the temperature at which it is prepared. Acted 
on by hydrochloric acid, it evolves chlorine, and with sulphu- 
ric acid, oxygen is given off. It is preferred to litharge for 
glass making. 

The chlorid and iodid of lead possess no particular inter- 
est ; the latter crystallizes in beautiful yellow scales from 

Describe the metal. How does water affect lead ? § 610. Describe 
the protoxyd of lead. The other oxyds. What use is made of Utharge? 



334 



METALLIC ELEMENTS. 




its solution in hot water. The sulphuret of lead is the na- 
tive galena already mentioned, and occurs in brilliant cleav- 
able cubes. Sulphureted hydrogen throws down a black sul- 
phuret from all soluble salts of lead, being the best test of 
its presence. 

§ 612. Zinc precipitates it from its solutions by electrical 
action (^ 247) in beautiful crystalline plates of 
metallic lead, which assume a branching form, 
often an inch or two in length, and hence called 
the lead tree, or arbor saturni, from the alche- 
mistic name of this metal. The acetate or nitrate 
may be employed ; an ounce of the salt is dis- 
solved in two quarts of water, and a piece of 
clean zinc, suspended in it by a thread, the 
precipitation is gradual and occupies one or 
two days. The arrangement is seen in the an- 
nexed figure. 

§613. Carbonate of Lead ; White Lead; PbO, CO2. — 
This salt is found beautifully crystallized in nature, but is 
prepared arfificially in very large quantities, for the purposes 
of a paint. This pigment is obtained by casting lead in 
very thin sheets, which are then rolled up into a loose scroll 
and placed in a pot over a small quantity of vinegar, and so 
arranged as not to project above the pot, nor touch the 
vinegar. Many thousands of these pots are arranged in suc- 
cessive layers over each other, with boards between, and 
the interstices filled with spent tan, or fermenting stable 
dung, which gives a gentle heat to the acid. After a time 
the lead is completely converted into an opake white crust 
of carbonate. The theory of this process will be explained 
when we describe the acetates of lead, (organic chemistry.) 
White lead is now largely adulterated by sulphate of baryta, 
but the fraud may be easily detected by dissolving the car- 
bonate in an acid, when the sulphate of baryta will be left 
behind. Carbonate of lead is highly poisonous. 



VI. URANIUM. 



§ 614. This is a very rare substance, found only in pitch- 
blende, uranite, and a few other rare minerals. Its chemical 
history is, however, possessed of considerable interest. 



§ 612. How is metallic lead produced from its solution? § 613. How 
is the carbonate prepared, aud for what is it used ? § 614. What is said 
of uranium? 



COPPER. 335 

There are three oxyds of uranium, viz., UgOg, UgOg, and 
U4O5. The metal is usually obtained as a dark powder, 
but can be condensed into a white malleable form. The 
phosphate of uranium and copper [uranite) is one of the most 
beautiful of minerals. It forms beautiful yellow salts. 

IX. COPPER. 

Equivalent, 31*65. Symbol, Ca. Density, •839. 

^ 615. Copper has been in familiar use since the times of 
Tubal Cain, and is one of the most important metals to the 
wants of society. It is often found in the metallic state. 
The metallic copper of Lake Superior is associated with na- 
tive silver, and small proportions of silver are also often alloyed 
with the copper. One mass from this region nov/ at Wash- 
ington, weighs over 3000 pounds. Its most usual ores are 
the red oxyd of copper and the copper pyrites, or sulphuret 
of copper and iron. The blue and green malachites, or car- 
bonates of copper, and several other salts of this metal, are 
also found in the mineral kingdom. Copper is very malle- 
able, and is the only red metal except titanium. It 
fuses at 1996"^, and has a density of 8 89, which maybe in- 
creased to 8*95 by hammering. It does not change in dry 
air, but in moist air becomes covered with a green coat of 
carbonate. - It is stiffened by hammering or rolling, and 
softened again by heating and quenching in water. It may be 
drawn into very fine wire, which is an excellent conductor 
of heat and electricity, and is much used in electro-magnet- 
ism, and for tlje telegraphic conductors. 

Nitric acid is the proper solvent of copper, sulphuric and 
hydrochloric acids scarcely acting upon it. It forms two 
oxyds, the protoxyd and the suboxyd. 

§ 616. The first, or black oxyd of copper, CuO, is the 
base of all the blue and green salts of copper. It is formed 
by decomposing the nitrate w^ith heat. It is black and 
very dense, quite soluble in acids, and forms many important 
salts which are isoraorphous with those of magnesia. It 
yields all its oxygen to organic matters at a red heat, and 
for this purpose is much used in their analysis. 

The suboxyd or red oxyd of copper, Cu^ O, is found native 

§ 615. In what state does copper occur in nature ? Describe its prop- 
erties. § 616. What are the most important facts relative to the black 
oxyd of copper ? Describe the suboxyd. 



336 



METALLIC ELEMENTS. 



in beautiful octahedral crystals, and is also formed when cop- 
per is oxydized by heat. This oxyd communicates to glass 
a magnificent ruby red color. The chlorids and iodids 
of copper are of no great importance. 

§ 617. Sulphate of Copper ; blue vitriol, CuO SO3 + 5HO, 
is an important salt, crystallizing in large beautiful blue 
rhombs, which are soluble in 4 parts of cold or 2 parts of hot 
water. It loses its water by a gentle heat and falls to 
a white powder. It is much used in dyeing, and for ex- 
citing galvanic batteries. With ammonia it forms a dark 
blue crystallizable compound. 

§ 618. Nitrate of Copper, CuO, NO, -f 3H0, is formed by 
dissolving copper in nitric acid to saturation, and is a deep 
blue crystallizable, deliquescent salt, very corrosive, and easily 
decomposed ; a paper moistened with a strong solution of this 
salt cannot be rapidly dried without taking fire, from the 
decomposition of the nitric acid. 

Ammonia detects the smallest traces of this metal in 
solution, by the deep violet blue of the ammoniacal salt of 
copper which is formed. Iron precipitates it from its acid 
solutions as a brilliant red coating. 

CLASS V. METALS WHOSE OXYDS ARE WEAK BASES 
OR ACIDS. 



I. VANADIUM. II. TUNGSTEN. III. MOLYBDENUM. 
IV. COLUMBIUM. V. TITANIUM. 

^ 619. The first five metals of this class are so rare that 
we shall dwell on them very briefly. 

1 . Vanadium is described as a very infusible, brittle, 
white metal, and dissolved only by aqua regia, affording a 
blue solution. It is found only in one or two very rare 
minerals, as in the vanadinite or vanadiate of lead, acting 
the part of an acid. It appears to be closely allied to 
chromium. 

2. Tungsten, so named in allusion to its great weight, is 
found as tungstic acid in two or three rare minerals, viz. 
wolfram and tungstate of lime. The native tungstic acid has 
also been observed at Monroe, Ct. Metallic tungsten re- 

§517. Describe sulphate of copper. §618. What is the nitrate? 
How does it affect organic matter? How is copper detected? §619. 
Enumerate the five metals described in this section. What is vanadi- 
um? Deseribe tunsfsten. 



TITANIUM. 337 

sembles vanadium in physical characters, but it takes fire 
when heated in air in a state of division. It has a density 
of 17-4. 

There are two oxyds of tungsten : the first (WO^) forms 
no salt ; the second, tungstic acid, (WO 3,) is a yellow pow- 
der, insoluble in water, but is easily dissolved in ammonia. 

3. Molybdenum. — Sulphuret of molybdenum is a rather 
common mineral, found in soft scales resembling graphite. 
The metal is obtained from its oxyd and is very infusible, 
white and brittle, having a density of 8-6. 

It forms three oxyds, MO, MO^, MO 3, of which the last 
only has much importance ; it resembles tungstic acid in 
being soluble in alkalies. It forms a beautiful yellow salt 
with lead, which is found native. The native sulphuret may 
be converted into impure molybdic acid by heat. 

4. Columhium, or Tantalum. — This metal was named 
after this country by Mr. Hatchett, its discoverer, who found 
it among some ores sent to the Royal Society in London, 
by Gov. Winthrop, from Connecticut. 

Columbite (columbate of iron) is found at Haddam and 
Middletown, sometimes in large crystals. Prof. Shepard 
procured the metal in a crucible lined with charcoal, as a 
dull, very infusible, brittle body, having a density of 5-7. 
Columbium forms two oxyds, TO2 and TO3. The last is 
columbic acid, a white powder, soluble in acids, and forms 
almost insoluble salts with the alkalies and metallic oxyds. 
It is in this acid that the oxyds of the two newly proposed 
metals, pelopium and niobium, are supposed to exist. 

5. Titanium. — This metal is found crystallized in small 
brilliant cubes of a copper-red color in the slags of some 
iron furnaces. Its oxyd, beautifully crystallized, is well 
known to mineralogists, as rutile, anatase, and Brookite, three 
minerals specifically distinct, but chemically identical. Ti- 
taniferous iron ore is also an abundant mineral. 

Titanic acid, TiO^, is soluble in strong hydrochloric acid, 
but on dilution and boiling is all precipitated. It is a white 
insoluble powder, much resembling silica. It gives a 



(2.) What oxyds of tungsten are -named ? (3.) How is molybde- 
num found? What oxyd and what native salt of it are named? (4.) 
Give the history of columbium. In what mineral is it found? Describe 
its oxyds (5.) How is titanium found? What minerals contain it? 
Describe titanic acid. 

29 



338 



METALLIC ELEMENTS. 



peculiar tint to porcelain, and is used for this purpose in 
preparing artificial teeth. 

V. TIN. 

Equivalent^ 58-82. Symbol, Sn. {Stannum.} Density, 7'29, 

§ 620. Tin is one of those metals which have been known 
from the most remote antiquity. The mines of Cornwall 
have been worked for the oxyd of tin, since the times of 
the Greeks and Phcenicians. It has been found in this 
country only at Jackson, N. H., in small quantities. Tin is 
a white metal with a brilliant lustre, not easily tarnished, 
and resisting the action of acids to a remarkable degree. 
It is soft, very ductile, laminable, and malleable. Tin fotl 
is made not over yoVo ^^ ^" ^"^^ ^^^ thickness, or even much 
thinner. A bar of tin when bent gives a peculiar crackling 
sound, from the disturbance of its crystalline structure, for- 
merly called the cry of tin. It is one of the best conductors 
of heat and electricity. 

^621. Tin has a density of 729 and fuses at 442*^. 
Its alloys are very valuable; gun-metal (copper 90, tin 10) 
is one of the strongest alloys known, of a reddish yellow ; 
while bell-metal (copper 78, tin 22) is a very sonorous and 
brittle alloy, of a pale yellow ; and speculum metal (copper 
70 to 75, and tin 25 to 30) is a brilliant, almost white, and 
excessively brittle alloy. Pewter is a mixture of tin and 
antimony or lead. Tin-plate is only sheet-iron coated with tin. 

Strong nitric acid docs not dissolve tin, but the addition 
of a little water causes a violent action, and the tin is 
speedily oxydized. 

§ 622. There are three oxyds of tin : the protoxyd, SnO ; 
the sesquioxyd, Sn^Og ; and the peroxyd, SnOg. (1.) This 
is obtained by precipitating a solution of protochlorid of 
tin with an alkaline carbonate, which yields a bulky hydrate 
of the protoxyd. It is a very unstable compound, passing into 
the peroxyd at a very moderate heat. (2.) The sesquioxyd is 
a grayish powder, which has been but little examined. 



§ 620. What history is ^iven of fin ? What is its equivalent and g^en- 
eral properties ? § 621. Give its density and fusibility. What is said of 
its alloys with copper? What is tin-plate ? and what pewter? How 
does strong nitric acid affect it ? § 622. What oxyds of tin are there ? 
What is the protoxyd ? 



BISMUTH. 339 

(3.) The peroxyd is found native in the beautiful crystallized 
tin stone. It may be obtained in two very unlike conditions, 
(1) a soluble, and (2) an insoluble, (i.) When the perchlorid 
is precipitated by an alkali, the bulky white precipitate of 
hydrated peroxyd which appears, is easily soluble in acids 
(2.) But ii tin is acted on by an excess of moderately strong 
nitric acid, a white insoluble powder is formed, which is not 
acted on by the strongest acids. Heat converts both into a 
lemon-yellow powder which dissolves in alkalies, but not in 
acids, and which is known as stannic acid ; ii reddens test- 
paper and forms salts. The ' putty^ used to polish stone, 
glass, and razor strops, is the peroxyd of tin. 

§ 623. Protocklorid of tin^ which is prepared by dissolv- 
ing tin in hot hydrochloric acid, is a powerful deoxydizing 
agent, and reduces the salts of silver, mercury, platinum, &c., 
to the metallic state. It is a delicate test of the presence of 
gold, with which it forms the beautiful purple of cas- 
sius, used in porcelain painting ; which is probably a com- 
pound of sesquioxyd of tin and oxyd of gold, (AuO,Sn2 03.) 
The anhydrous protochlorid is formed by heating pro- 
tochlorid of mercury with powdered tin. 

^ 624. Perchlorid of tin is a thin fuming liquid, long known 
as the fuming liquor of Lahavius. It is formed by distilling 
a mixture of 1 part of powdered tin and 5 of corrosive sub- 
limate. The tin mordant used by the dyer is formed by dis- 
solving tin in hydrochloric acid, with a little nitric, at a low 
temperature, or by passing chlorine gas through the proto- 
chlorid. 

The suiphurets of tin correspond to the chlorids. The 
bisulphuret [aurum musivum) is used as a bronze color for 
imitating gold in ornamental painting and printing. 

The alchemistic name for this metal was Jove^ and tha 
preparations of tin are still called Joirial preparations. 

VI. BISMUTH. 

Equivalent, 7095. Symbol, Bi. Density, 982. 
§ 625. Bismuth is found native, and also in combination 

Describe the peroxyd. What two modifications of it are named? 
How does heat affect them? What is 'putty?' §623. How is proto- 
chlorid of tin employed as a reagent? For what is it a delicate test? 
§ 624. What is perclilorid of tin, and how prepared ? What is the tin 
mordant ? AVhat suiphurets of tin are there? 



340 



METALLIC ELEMENTS. 



with Other substances. Native bismuth is found at Mon- 
roe, Conn. It is a brittle, highly crystalline metal, of a 
reddish-white color, with a density of 9*82, and fuses at 
497°. It is obtained in large and beautiful cubical crystals, 
by perforating the crust of a mass which is just cooling from 
a state of fusion in a crucible, and pouring out the still fluid 
interior. The vessel will be lined with a multitude of brill- 
iant crystals. 

It dissolves in nitric acid, but like other metals of this 
class, does not decompose water under any circumstances. 

^ 626. Two oxyds of bismuth are known. The protoxyd 
(BiO) is formed by gently igniting the subnitrate, and is a 
yellowish powder, easily soluble in acids, and is the base 
of all the salts of bismuth. It is, however, a very feeble 
base, since even water decomposes its salts. The peroxyd 
(Bi^jOg) is not of much interest. 

§"^627. The nitrate of bismuth (BiO, NO^ + SHO) is the 
most interesting of its salts. It may be obtained from a 
strong solution in large transparent crystals, which are de- 
composed by water. It is a striking and instructive exper- 
iment, to turn the solution of the nitrate of bismuth into a 
large quantity of water, when it is immediately decomposed, 
with the production of a copious white precipitate of subni- 
trate of bismuth. This is owing to the superior basic power 
of the water which takes a part of the nitric acid. The 
white precipitate is a basic nitrate, (BiOjNO^ + SBiOjHO.) 
Chlorids of tin and antimony are decomposed in the same 
manner. 

^ 628. The alloy of bismuth known as Newton's fusible 
metal, is formed of 8 parts bismuth, 6 parts lead, and 3 parts 
tin, and melts below 212°. It is much used in taking casts 
of medals. The expansion of bismuth in cooling, renders 
it a valuable constituent of all alloys, where sharpness of 
impression in casting is important. 



VII. ANTIMONY. 

Equivalent, 129'04. Symbol, Sb, (Stibium.) Density, 6'7, 
^ 629. This metal is derived chiefly from its native sul- 

§ 625. What is the color and fusibility of bismuth? Describe its 
crystals^ and the mode of obtaining them. § 626. How many oxyds has 
this metal ? § 627. What is the most interesting property of the nitrate ? 
§ 628. W^hat is the composition of Newton's fusible metal ? 



ANTIMONY. 341 

phuret, which is a rather abundant mineral. The metal is 
obtained by fusing the sulphuret with iron-filings, or car- 
bonate of potash, which combines with the sulphur and sets 
free the metal. It is a white brilliant metal with a blue tint, 
forming broad rhomboidal crystalline plates. It is very brit- 
tle, and like bismuth may be reduced to a fine powder. It 
fuses at about 1000°, or low redness, and at a higher heat 
is volatilized. It dissolves in hot hydrochloric acid, but in 
nitric acid the insoluble white antimonic acid appears on 
digestion. 

Its alloy with lead is type-metal, which, like the alloys 
of bismuth, gives very sharp casts, by reason of the expan- 
sion it suffers in cooling, although it is remarkable that both 
of the constituent metals shrink when cooled separately. 
Finely powdered antimony is inflamed in chlorine gas, form- 
ing the terchlorid. 

^ 630. Three oxyds of antimony are known, viz : 

(1) Oxyd of antimony. SbOg. — This oxyd may be ob- 
tained by digesting the precipitate from chlorid of antimony 
by water, with carbonate of potash or soda, or by burning 
antimony in a red-hot crucible. It is a fawn-colored insol- 
uble powder, anhydrous, and volatile when highly heated in a 
close vessel. Boiled with cream of tartar, (acid tartrate of 
potash,) it forms the well-known tartar emetic, which may 
be obtained- in crystals from the solution. 

The glass of antimony is an impure fused oxyd, prepared 
for the purpose of making tartar emetic. Heated in air, this 
oxyd gains another equivalent of oxygen, and forms — 

^631. {2.\Antimonious Acid, SbO^. — This is a gray pow- 
der, not volatile, insoluble in acids, unless recently precip- 
itated. Its hydrate reddens litmus paper, and combines 
with alkalies. 

Antiw.onic acid, Sb05, is formed as already stated, when 
antimony is digested in an excess of strong nitric acid. It 
dissolves in alkalies, with which it forms definite salts, 
that are again decomposed by acids, hydrate of antimonic 
acid being thrown down. The hydrate loses its water be- 
low a red heat, becoming a crystalline fawn-colored powder, 



§ 629. How is antimony obtained ? What are its properties ? § 630. 
How many compounds does antimony form with oxygen? § 631. De- 
scribe the two acids of antimony. 

29* 



342 



METALLIC ELEMENTS. 



and by a higher heat one equivalent of oxygen is expelled, 
aritimonious acid being formed. 

§ 632. Inhere are cJilorids and sulphurets of antimony, cor- 
responding to the oxyd and to antimonic acid. 

The terchlorid, butter of antimony, SbClg, is made by dis- 
tilling the residue of the solution of sulphuret of antimony 
in strong hydrochloric acid. When a drop of the distilled 
liquid forms a copious white precipitate on falling into water, 
the receiver is changed, and the pure chlorid is collected. 
It is a highly corrosive fuming fluid, and by cooling forms a 
crystalline deliquescent solid. It is used in medicine as a 
caustic. Water decomposes it, but it dissolves in hydro- 
chloric acid unchanged; water poured into the solution 
throws down a bulky precipitate which is a mixture of oxyd 
and chlorid of antimony, and has long been known by the 
name of 'powder of aJgaroth. 

The bromid of antimony is a crystalline volatile com- 
pound. 

^ 633. The tersulphuret of antimony, SbS3, is the com- 
mon commercial sulphuret, and the beautiful crystallized na- 
tive mineral. 

The pent asulphuret of antimony, SbS^, is formed by boil- 
ing the tersulphuret with potash and sulphur, and throwing 
down the compound in question by an acid, as a golden yel- 
low sulphuret, known by the name of sulphur auratum, 
or golden sulphur of antimony. More generally, how- 
ever, the decomposition on adding an acid, as above, gives 
us the oxysulphuret of antimony, (SbSg + SbOg,) which is 
a characteristic reddish-orange precipitate. This is the sub- 
stance known as kermes mineral, and is an article of the 
older medical practice. The solution of sulphuret of anti- 
mony in caustic potash and sulphur, is a case in which sul- 
phuret of potassium is a sulphur base, and sulphuret of an- 
timony, a sulphur acid. 

VIII. ARSENIC. 

Equivalent, 75-21, Symbol, As. Density, 5884. 

^ 634. Metallic arsenic is found native in thick crusts, 
called testaceous arsenic, evidently deposited by sublimation. 



§ 632. Describe the terchlorld and its decomposition. § 633. What is 
said of the chlorid and sulphurets? What is kermes mineral? 



ARSENIC. 343 

It is however more usually obtained from roasting the ores 
of cobalt, nickel, and iron, with which metals it is often 
combined, forming arseniurets. The vapors of arsenious 
acid given out in the roasting, are condensed in a long hor- 
izontal chimney, or in a dome constructed for the purpose ; 
the first product being purified by a second sublimation. 
Arsenic is a very crystalline steel-gray metal, brittle, easily 
crystallized, and converted by contact of air into a dull cast- 
iron looking body. It cannot be sublimed unchanged in 
presence of air, but may be so in close vessels, at a tem- 
perature of 356°, without previously melting. Its vapor 
has a very powerful garlic-like odor, like phosphorus. This 
metal is known by druggists under the absurd name of co- 
halt^ and is sold in powder to destroy flies. Metallic arsenic 
is easily obtained by subliming the common white arsenic in 
a bottle of hard glass, like a cologne vial or oil bottle, with 
black flux, (^ 491.) The metal forms a brilliant black crust 
in the upper and cooler parts of the vessel. 

Arsenic forms two compounds with oxygen, viz : 
^ 635. (1.) Arsenious Acid — White Arsenic- — Rat's Bane, 
AsOg. — This well known poison is formed as just stated, 
when metallic arsenic is sublimed in air, or when any of 
the ores of arsenic are roasted. This acid is what is 
usually known as arsenic in commerce. When newly sub- 
limed, it is- a hard transparent glass, brittle, and with a density 
of 3*7. It slowly changes to a white opake enamel. As 
sold in commerce, it is usually reduced to a white powder, 
rarely found without adulteration. It sublimes at 380°, 
without change, and crystallizes in brilliant octahedrons, as 
may be well seen by heating a small quantity in a glass tube. 
Its vapor is inodorous, but if sublimed from charcoal it gives 
the peculiar garlic odor of metallic arsenic, being reduced 
to that state. It is soluble in about 10 parts of hot water, 
and is almost tasteless, which renders it the more danger- 
ous poison, since no warning is given to the victim who 
takes it, as in case of most other metallic poisons. The so- 
lution in water is acid to test paper, and deposits nearly all 
its arsenic in crystals, on cooling. Hydrochloric acid dis- 



§ 634. How is arsenic obtained, and what are its properties ? § 635. 
Describe arsenious acid. 



344 METALLIC ELEMENTS. 

solves it, as also do alkalies, which however do not form 
crystallizable salts with it. 

§ 636. Arsenic Acid, AsO^. — This acid is fornied by add- 
ing nitric acid to the solution of white arsenic, in hydrochlo- 
ric acid, as long as any red vapors of nitrous acid show 
themselves, and then carefully evaporating the solution to 
entire dryness ; a white porous subcrystalline mass remains, 
which is slowly soluble in water Its sohition is a powerful 
acid, quite similar in chemical characters to phosphoric acid. 
The analogy is so great that there is a compete similarity 
in constitution, and even in external appearance, between 
all the salts of these two acids. For every tribasic phos- 
phate we have an arseniate, not only similar in constitution 
but isomorphous, and so resembling it in all its exter- 
nal properties as not to be distinguished by the eye. Thus 
the tribasic phosphate of soda, {§ 533,) and the tribasic 
arseniate of soda are — 

Phosphate of soda, P03,2NaOHO+24Aq. 

Arseniate of soda, AsO^,2NaOHO + 24x\q. 

These, and many other facts, lead to the opinion that 
the elements are themselves isomorphous, and in fact ar- 
senic has no claim to the metallic character, but its lustre 
being in chemical properties and natural affinities associated 
with phosphorus. 

"^ 637. The chlorid of arsenic (AsClg) is a fuming volatile 
liquid decomposed by water, and very poisonous. The bro- 
mid and iodid are both crystallizable solids, also decomposed 
by water. 

The sulphurets of arsenic are natural compounds, used 
as pigments, and also in pyrotechny. The first, AS^, is a 
red transparent body called realgar, and AsSg is the 
golden yellow orpiment, formed when sulphureted hydrogen 
is passed through any of the soluble solutions of arsenic. 
A higher sulphuret, as S-. may be formed. 

^ 638. Arseniureted Hydrogen. — This is perhaps the most 
deadly poison known. It is a gas produced by the action 
of dilute sulphuric acid on an alloy of zinc and arsenic, 
or by the evolution of hydrogen in presence of arsenic or 



§ 636. How is arsenic acid obtained? To what other acid is it alHed, 
and how ? What is the real character of arsenic ? § 637. Describe the 
sulphurets. § 638. What are the characters oi arseniureted hydrogen ? 



ARSENIC. 345 

arsenious acid. This gas is at once absorbed by a solution 
of sulphate of copper. It burns with a peculiar blue flame, 
and deposits metallic arsenic or arsenious acid. Marsh's 
test for arsenic depends on the generation of this gas. 

^ 639. Detection of Arsenic as a Poison. — The fearful use 
which is made of this terrible poison in destroying human 
life renders it of the first moment, that we should know 
easy and certain process for its detection. Accordingly we 
find that very numerous methods have been proposed for 
this purpose, a few of which we will briefly mention. 
When a fluid, or other s\}ihsidi,r\ce free from organic matter^ is 
to be examined for arsenic, there are many tests which we 
can apply. (1.) Sulphureted hydrogen throws down the 
yellow sulphuret (orpiment) in acidulated solutions of arse- 
nious acid ; this is redissolved by ammonia and again 
precipitated by acids. (2.) Nitrate of silver produces a 
yellow precipitate of arsenite of silver in solutions of arse- 
nious acid, if a trace of ammonia is present ; but the precipi- 
tate does not appear in an acid solution, and an excess of 
ammonia dissolves it. (3.) Sulphate of copper gives a brill- 
iant green precipitate of arsenite of copper, [ScheeVs green,) 
in alkaline solutions of arsenious acid, which precipitate is 
redissolved by ammonia in excess. (4.) A clean slip of 
metallic copper placed in a solution of arsenious acid, is soon 
coated with a gray deposit of metallic arsenic; this is 
known as ReincKs test. 

^ 640. All these tests taken collectively, constitute to the 
mind of the chemist a perfect demonstration of the presence 
of arsenic ; but they are liable to many objections arising 
from the presence of organic matters ; of impurity in rea- 
gents ; and from the possible presence of other metallic mat- 
ters, as antimony, which forms a brick-red or yellowish sul- 
phuret; and cadmium, whose sulphuret much resembles orpi- 
ment. It is therefore always demanded in judicial inves- 
tigations that no proof of the presence of arsenic shall avail 
except that of subli^ned metallic arsenic. 

^ 641. Reduction of Arsenic. — When it is possible to ob- 
tain from the suspected substance any grains of white oxyd of 
arsenic, these are carefully selected for the purpose of examin- 
ation. If not, the yellow sulphuret^ obtained from the solution 

§ 639. What are some of the means of detecting the presence of this 
poison ? § 640. What other bodies resemble it in its reactions ? 



346 METALLIC ELEMENTS. 

by sulphureted hydrogen is employed, to produce the metallic 
arsenic. Either of these substances is introduced into a 
small tube of hard glass drawn out at the lower part as here 
represented, small fragments of charcoal or black 
flux{^ 491) are then added, and the tube filled there- 
with, to the shoulder, [a.) Its interior being wiped 
out, the flame of a small spirit-lamp is applied to 
the upper part of the mixture to expel any moisture 
it may contain, which is next carefully removed by 
bibulous paper. The charcoal or flux is then 
gradually heated to redness from a to h, and the heat 
slowly carried down below Z>, until the lower part of 
the tube is fully red. If any arsenic is present it 
, is sublimed, rendered metallic by passing the red- 
hot charcoal, and deposited in a brilliant ring just 
H , above the shoulder, as seen in the figure. For 
further proof, the tube may be drawn off at a in the 
lamp-flame, and the metallic arsenic chased about 
by the heat until it is all converted into arsenious acid, 
which a magnifier shows to be in brilliant white octahedral 
crystals. 

^ 642. But the most common and most difficult case of 
testing for arsenic is when the fluids of the stomach, ejected 
by the patient, or the stomach itself and its contents, are to 
be examined. The organic matters present in all such 
cases, render the liquid tests quite worthless, and oblige 
us to have recourse to a method of which a brief sketch 
only can be presented. The suspected fluid and the solid 
parts cut small, are placed in a large porcelain capsule with 
a considerable quantity of pure hydrochloric acid, and as 
much water as will make the mixture thin. This mixture 
is heated on a water bath, and while hot, small portions of 
20 or 30 grains of chlorate of potash are added to the mix- 
ture, at short intervals. The chlorine evolved by this treat- 
ment completely decomposes the organic matters, and the 
final result is the production of a yellow transparent fluid, 
which can easily be filtered. From this, sulphureted hydro- 
gen in excess will throw down all arsenic, antimony, &c., 
w^hich may be present ; and after resolution and reprecipita- 
tion the suspected sulphuret of arsenic may be reduced 

§ 641. How are we to obtain it in a metallic state? § 642. How do 
we ascertain its presence when mixed with organic matters ? 



TELLURIUM. 



347 



in the same way as has been just described. Another 
mode of reduction, however, is much to be preferred, where 
cyanid of potassium is employed in the reduction tube, in 
place of the black flux, with about three parts dry carbonate 
of soda, and the sulphuret. This is a very brief account 
of the late method by Fresenius and Von Babo of testing 
for arsenic. 

^ 643. Marshes test is one which is very convenient, sim- 
ple, and if used with care, satisfactory in most cases. It 
depends on the formation of arseniureted hy- 
drogen. The suspected substance is placed in 
a flask with the materials to generate hydrogen, 
(§ 375.) This gas, as it issues from a jet, is set 
on fire, and if arsenic is present in the mix- 
ture, the flame burns with a peculiar blue 
light, and a clean plate of glass or porcelain 
held over it, is at once blackened by a film 
of metallic arsenic. The annexed figure 
shows a convenient form of this appara- 
tus. The materials for hydrogen and the 
suspected body are put in the lower bulb, and 
dilute sulphuric acid being turned into the 
upper bulb, hydrogen gas is generated, and may be delivered 
at will by the stop-cock and jet. Extremely minute traces 
of arsenic may be detected by this test. Antimony presents 
a somewhat similar spot, but may easily be distinguished 
from arsenic by a practised eye. It must be observed that 
all the reagents employed in this apparatus, the zinc, the 
acid, and even the glass of the vessel, may contain arsenic. 




IX. TELLURIUM. 

§ 644. Tellurium (Te. 64*14) is a very rare substance, 
more analogous to sulphur in its chemical relations than to 
the metals. It is found native or alloyed with gold, and is 
also combined with bismuth, silver, &c., in several very rare 
minerals, as telluric bismuth^ graphic tellurium, and auro- 
tellurite . 

When pure, it is a tin-white, brittle substance, with a me- 



§ 643. Describe Marsh's test. What objections are there to his 
method? §644. What are the characteristics of teUurium ? To what 
other body is it allied ? 



348 METALLIC ELEMENTS. 

tallic lustre, and a density of 626. It melts at low redness, 
is very volatile, and is a bad conductor of heat and electri- 
city. It burns when strongly heated in the air, and forms 
tellurous acid, TeO^. Telluric acid (TeOg) can also be 
formed from tellurous acid, by a process which need not 
now be described. 

X. OSMIUM. 

^ 645. Osmium (Os, 99*56) is one of the rare metals 
which are associated with platinum. It has a density of 10-, 
and is of a bluish-white color, neither fusible nor volatile, but 
takes fire in the air, forming osmic acid. Dr. Hare states 
that this acid is very poisonous, as he has personally expe- 
rienced. Osmium forms four oxyds, viz: OsO, Os^Og, 
OsOg, and OsO^. Osmiate of potash is formed when the 
metal is fused with nitre. It combines with sulphur and 
phosphorus. 

CLASS VI. NOBLE METALS, WHOSE OXYDS ARE RE- 
DUCED BY HEAT ALONE. 

I. GOLD. 

Equivalent, 99*44. Symbol, Au. Density, 19*26. 

§ 646. This valuable metal is found only in the metallic 
or native state, being very widely diffused in small quanti- 
ties in the older rocks. From these, by the action of various 
causes, it finds its way into the sand of rivers, and is distrib- 
uted in small quantities, in many wide spread deposits of 
coarse gravel or shingle, — as on the eastern flanks of the 
Ural Mountains, and over a wide belt of country in Virginia, 
the Carolinas, Georgia, and Alabama. These diluvial de- 
posits furnish nearly all the gold of commerce, by a process 
of washing, and amalgamation with mercury. Large 
masses of gold sometimes occur, as one of twenty-eight 
pounds in North Carolina, and in Siberia a mass was 
found, now in the Imperial Cabinet of St. Petersburg, weigh- 
ing nearly eighty English pounds. Generally, however, 
it occurs only in minute grains. It is also found in veins 

§645. With what body is osmium associated? What are its prop- 
erties? What is the sixth class of metals? § 646. How does gold oc- 
cur in nature ? How is it obtained ? 



MERCURY. 



349 



of quartz, in compact limestone, and distributed in iron 
pyrites. Native gold is usually alloyed with silver. 

^ 647. Gold is distinguished by its splendid yellow color, 
its brilliancy, and freedom from oxydation, by its extreme 
malleability and ductility, by its high specific gravity, (19-26 
to 19*5,) and by its indifference to nearly all reagents. It 
fuses at 2016° F., and is dissolved only by aqua regia, 
(^ 419,) by nascent cyanogen, and by selenic acid. The 
first is the solvent commonly known, and the solution con- 
tains the perchlorid of gold. 

§ 648. Gold forms two very unstable oxyds, (Au^O and 
^^2 O3,) which are decomposed, even by light. Two corres- 
ponding chlorids also exist. The perchlorid is a very deli- 
quescent salt, forming a red crystalline mass, soluble in 
ether, alcohol, and water. Metallic gold is deposited in ele- 
gant crystalline crusts from the ethereal solution. Ammonia 
throws down from solutions of gold an olive-brown powder, 
(fulminating gold,) which when dried explodes with heat, 
or by percussion. 

§ 649. The solution of protosulphate of iron throws down 
gold from its solutions in a very fine brown powder, which is 
green, as seen by transmitted light, when diffused in w^ater. 
The protochlorid of tin also forms a characteristic purple 
precipitate in gold solutions, (§ 628.) called the purple of cas- 
sius, which is a compound of tin and gold. Gilding of orna- 
mental work is usually performed by gold leaf ; but other met- 
als are gilded either by applying it as an amalgam with 
mercury, the mercury being afterwards expelled by heat, 
or preferably "by the new process of galvanic gilding from a 
solution ofihe cyanid of gold and potassium, (§ 247.) Gold 
wash, as it is called, is applied by a mixture of carbonate of 
soda or potash in excess, with oxyd of gold, in which small 
articles cleansed in nitric acid are boiled, and thus become 
perfectly covered with a very thin film of gold. 

II. MERCURY. 

Equivalent^ 101-26. Symbol, Hg, (Ht/ drag 2/ rum.) Den- 
sily, 13-5. 
§ 650 This is the only metal which is fluid at ordinary 

§ 647. Describe this metal. What is its usual solvent ? § 648. How 
many oxyds of gold are there ? Describe the perchlorid. § 649. What 
tests distinguish gold? How is gilding effected ? 
30 



350 NON-METALLIC ELEMENTS. 

temperatures. It is found as native or running mercury in 
Spain and Carniola, and also as cinnabar or sulphuret of mer- 
cury, but is a rather rare and costly metal. It has never 
been found in this country. The alchemists supposed it to 
be silver enchanted, {quick- silver,) and made many efforts to 
obtain from it the solid silver it was supposed to contain. 

Pure mercury is a silver-white, fluid metal, unchanged by 
air, and very brilliant. Cooled below 40° it solidifies, and 
is then as malleable as lead. It crystallizes at this degree 
of cold in cubes. It boils at 660°, and forms a colorless, very 
dense vapor. Even at 60°, a very rare vapor of metallic mer- 
cury (^ 129) rises from it. If heated in the air at above 600°, 
it slowly passes to the condition of red oxyd of mercury, 
which is its highest combination with oxygen. 

^651. The uses of mercury are numerous and important 
in the arts, and also in medicine. It forms alloys (amal- 
gams) with many other metals ; with tin it constitutes the 
brilliant coating of glass mirrors, (called silvering,) and it is 
of indispensable importance in procuring gold and silver 
from their ores. Its use in filling thermometers and barom- 
eters (§ 76) has already been described. 

Nitric acid dissolves mercury very rapidly even in the 
cold ; hydrochloric acid scarcely acts on it, and sulphuric 
only by the aid of heat, when it forms an insoluble sul- 
phate of mercury, evolving sulphurous acid, (§ 285.) The 
equivalent of mercury is often stated at 202*52, on the sup- 
position that the gray oxyd is the protoxyd ; but this seems 
to be more properly considered as a suboxyd, and the real 
protoxyd as the red oxyd. On this view the equivalent is 
stated at 101-26. 

Mercury may be so finely divided- as to lose its metallic 
appearance entirely ; as in blue pill, mercurialized chalk, 
(creta cum hydrargyro,) and mercurial ointment, which do 
not, as has sometimes been stated, contain the suboxyd of 
mercury, but only mercury in a state of very minute mechan- 
ical division. 

^ 652. The gray, or sxihoxyd of mercury , Hg2 0, is formed 
by digesting calomel in caustic potash, or by adding the 
same reagent to a solution of the nitrate of the suboxyd of 



§650. How is mercury found in nature? What are its properties? 
§ 651. What are the uses of this metal? How do acids act upon it? 



MERCURY. 351 

mercury. It is an insoluble, dark-gray powder, which is 
easily decomposed into metallic mercury and the red oxyd. 

The red oxyd, or protoxyd, red precipitate^ HgO, is 
prepared in the large way by heating the nitrate very cau- 
tiously, until i-t is quite decomposed, and a brilliant red crys- 
talline powder is left. It may also be formed by healing 
metallic mercury for a long time in a glass vessel nearly 
closed, and in this form is the preparation to which the old 
name of red precipitate per se was applied. Heat decom- 
poses this oxyd into oxygen and metallic mercury. It is, 
like the oxyd of lead, slightly soluble in water, and gives 
to it an alkaline reaction. It is a dangerous corrosive 
poison. 

^ 653. The chlorids of mercury correspond to the oxyds, 
and are both very important compounds. 

(1.) The suhchlorid of mercury, [calomel^) Hg2Cl, is a 
familiar medicine, and is easily formed by precipitating a so- 
lution of sub-nitrate with common salt. A white, insoluble, 
tasteless powder falls, which is the calomel. Even strong 
acids when cold do not affect it ; but it is instantly de- 
composed by alkalies and the suboxyd produced. Heat 
sublimes it unchanged. Its complete insolubility at once 
distinguishes this safe and mild substance from the highly 
poisonous compound — 

(2.) Corrosive Sublimate, or Chlorid of Mercury , HgCl. — 
This salt is most economically prepared by the double decom- 
position of sulpl>ate of mercury, by common salt, which by 
simple interch^ange gives corrosive sublimate and sulphate of 
soda, (HgO, S03 + NaCl = HgCH-NaO,S03.) The chlo- 
rid is also formed by dissolving the red precipitate in hot 
chlorohydric acid. Corrosive sublimate is a very heavy crys- 
talline body, soluble in about 15 parts of cold water, and 
in two or three parts of hot, giving a solution which pos- 
sesses the most distressing and nauseous metallic taste, 
and is a deadly poison. It is also soluble in alcohol and 
ether. It melts and sublimes a little below 600°. Al- 
bumen completely precipitates it, and the whites of eggs 
are therefore an antidote for this poison. For the same 

§ 652. How many ox^^ds does mercury form ? Describe the prepara- 
tion of the red oxyd. § 653. How many chlorids are there? How is 
calomel prepared? What is the process for obtaining corrosive subli- 
mate ? How does it differ from calomel ? Describe the antidote for this 
poison and its effect npon it. What uses are made of ^i-'— '-^ " '* 



352 METALLIC ELEMENTS. 

reason it is, doubtless, that timber and animal substances 
are preserved from decay, as in the kyanizing process, by- 
steeping in corrosive sublimate. The albuminous portions 
of wood suffer decay sooner than the vegetable fibre, and 
these are rendered completely indestructible in the process 
of Mr. Kyan, which is now in use in our national ship-yards. 

^ 654. There are two iodids of mercury, Hg^I and Hgl. — 
The second is a brilliant scarlet-red precipitate, form- 
ed by adding solution of iodid of potassium or hydriodic 
acid to a solution of corrosive sublimate. The iodid is 
at first yellow, but soon passes by a very interesting mole- 
cular change to the splendid scarlet crystalline powder be- 
fore noticed. It cannot be used as a pigment on account of 
its instability. 

^655. Two sulphurets of mercury, Hg^S and HgS, ex- 
ist, the first of which is formed when sulphureted hydro- 
gen is passed through a solution of subnitrate of mercury, 
and is a black powder. The sulphuret, HgS, or cinnabar, 
is formed when the nitrate of mercury (nitrate of the red 
oxyd) is treated with sulphureted hydrogen. It is a black 
precipitate, but turns red when sublimed, and forms the famil- 
iar pigment vermillion. This is the common ore of the 
quicksilver mines. 

^ 656. The nitrates of mercury. — The action of nitric 
acid on mercury varies with the temperature and the strength 
of the acid. In the cold, dilute nitric acid dissolves mer- 
cury, forming a neutral nitrate of the sub-oxide; but if the 
mercury is in excess, a salt is deposited in large and trans- 
parent white crystals, which are nitrate with excess of base. 
If hot and strong, the iiitrate of the red oxyd is formed, 
which is a very soluble salt not crystallizable. A basic salt 
of this oxyd may also be formed, which is decomposed by 
water. 

§ 657. Sulphate of mercury (HgO SO 3) results as an in- 
soluble, white, subcrystalline powder, by the action of the 
strong acid on metallic mercury, (§ 285.) Sulphurous acid is 
freely evolved. Water decomposes this salt, especially if 
boiling, removing a part of its acid, by which a yellow basic 



§654. Describe the iodid of mercury. §655. How many sulphurets of 
mercury are there 1 What is vermillion ? § 656. How are the nitrates 
of mercury obtained ? What is the nature of the nitrate of the red oxyd? 
§ 657. How is the sulphate formed ? 



SILVER. 353 

sulphate is formed, known as turpeth mineral. Its com- 
position is 3HgO, SO3. The sulphate of the gray oxyd, 
Hg^O, SO3, is formed as a crystalline white powder by 
treating a solution of subnitrate of mercury with sulphuric 
acid. It is slightly soluble in water 

^ 658. Ammonia produces many interesting compounds 
with the salts of mercury, of which the white precipitate, as 
it is called, is best known. This falls when chlorid of mer- 
cury in solution is treated with ammonia in excess, and is 
considered as a double amide and chlorid of mercury, HgCl 
and HgJNIH^. 

All the compounds of mercury are volatile at a red 
heat, and those which are soluble, whiten a slip of clean 
copper by depositing metallic mercury on its surface. 

III. SILVER. 

Equivalent, 108*12. SijmhoL Ag, (Argentum.) Density, 10-5. 

^ 659. The mines of Mexico and the Southern Andes 
furnish most of the silver of commerce, although many 
mines of this metal are found in Spain, Saxony, and the 
Hartz mountains. Galena, or the native sulphuret of lead, 
is also a constant source of silver, as it is rarely quite free 
from this precious metal. Silver is often found native, and 
also in combination with sulphur. 

The brilliant lustre and white color of this valuable metal 
are familiar to all. It is perfectly ductile and malleable, and 
in hardness stands between gold and copper. For the pur- 
poses of economy and in coinage it is essential to alloy it 
with about j\ part of copper, to render it sufficiently stiff and 
hard. 

Pure silver melts at 1873°, and when melted absorbs sev- 
eral times its volume of oxygen gas, which it parts with 
again on cooling. This renders silver a difficult metal to 
cast, and occasions the little projections and roughness usu- 
ally seen on silver which has been melted. 

Silver is obtained pure from its solutions in nitric acid 
by precipitation with metallic copper, as a finely divided, 
crystalline powder ; or by decomposing its chlorid by fusion 

§ 658. What is the nature of white precipitate ? What are the char- 
acteristics o^ mercurial compounds? § 6,59. From what sources is silver 
obtained? What are the characteristics of pure silver? 

30* 



354 METALLIC ELEMENTS. 

wiih two parts of dry carbonate of potash. Nitric 
acid dissolves silver in the cold with great rapidity, and if 
it contains any gold, this is left undissolved as a brown pow- 
der. 

Hydrochloric acid scarcely acts on silver, and sulphuric 
acid only when hot, forming the sulphate of silver, which 
is sparingly soluble in water. 

^ 660. Silver is parted from galena by a process called 
cupellation, or fusing the pulverized galena and a certain 
quantity of metallic lead, on a little thick cup or cupel of bone- 
ashes, in a muffle exposed to air. The lead oxydizes andis 
absorbed by the cupel, while the silver is left in a brilliant 
metallic button on the cupel. In the large way this process 
is much facilitated by the fact that the alloy of silver and 
lead is more fusible than pure lead, and the latter on cool- 
ing separates from the former, which may be drawn off, and 
contains all the silver. This small portion is cupelled while 
the great bulk of the lead is returned to the arts uninjured. 

§ 661. Three oxyds of silver are known by chemists: 
the suboxyd, Ag^ O ; the protoxyd, AgO ; and the per- 
oxyd, AgO^. We will now notice only the protoxyd. This 
is formed when the solution of silver in nitric acid is satu- 
rated with caustic potash, or when the chlorid of silver re- 
cently precipitated is digested in a solution of caustic pot- 
ash of density TS. It is a dark-brown or black powder, if 
prepared by the first mode, or quite black and dense by the 
second process. It is a base forming well-defined salts. 
Ammonia dissolves it readily, and it is also somewhat solu- 
ble in water, to which it gives an alkaline reaction. It is 
easily reduced by heat alone. Its solutions are at once de- 
tected by the bulky white curdy precipitate which they 
form with hydrochloric acid or with common salt. This 
white precipitate turns dark by exposure to light, 

§ 662. Chlorid of silver^ AgCl, is formed, as just remarked, 
when any soluble salt of silver is treated with a soluble 
chlorid or with hydrochloric acid. This substance fuses at 
a moderate red heat into a transparent pale yellow fluid, 
which is horny and tough when solid, and hence called 
horn silver, a form in which this metal is sometimes found in 
mines. It is easily reduced to the metallic state by the 

§ 660. How is it separated from lead? § 661. Describe the prepara- 
tion aud characters of oxyd of silver. § 662. Describe the chlorid. 



PALLADIUM. 355 

nascent hydrogen generated when zinc is acted on by dilute 
sulphuric acid in contact with the chlorid. Pure silver and 
chlorid of zinc result ; or, as already mentioned, it may be 
reduced by fusion with twice its weight of carbonate of 
soda or potash. 

The iodid and bromid of silver are, like the chlorid, insolu- 
ble in water, and very sensitive to light. The Daguerreotype 
and calotype (§ 62) are both dependent on the sensitiveness 
of these compounds to light, for the accuracy and beauty of 
their results. 

The sulphurets of silver are found native, and the tarnish 
which blackens silver articles on long exposure, is formed 
by sulphureted hydrogen in the air. 

§ 663. The nitrate of silver, AgO, NO^, is a salt which 
crystallizes in beautiful flattened tables of a hexagonal form, 
which dissolve in half their weight of hot water. By heat 
it fuses, and when cast in cylindrical moulds forms the 
slender sticks called lunar caustic, so much used by the sur- 
geon. Its solution has a disgusting metallic taste even when 
very dilute, and is a most delicate test of the presence of 
chlorine or any of its compounds. It blackens rapidly in 
contact with organic matter when exposed to the light, and 
forms an indelible ink, which is much used in marking 
linen. Solutions of cyanid of potassium will remove the 
stain produced by nitrate of silver. Metallic copper at 
once throws down metallic silver from the nitrate, and solu- 
tion of nitrate of copper is formed. Mercury precipitates 
metallic silver from a dilute solution, in beautiful tree-like 
forms, called arbor Dian(E. Ammonia, by acting on pre- 
cipitated oxyd of silver, forms a fulminating compound. It 
is extremely hazardous to deal with, as it explodes even 
when wet. 

IV. PALLADIUM. 

Equivalent, 53 27. Si/mbol, Fd, Density, ITS. 

§ 664. This very rare metal is usually found associated 
with ores of platinum, among which Dr. Wollaston discov- 

How can it be reduced? What are the relations of the silver com- 
pounds to light? What is the action of sulphureted hydrogen on silver? 
\ 663. Describe the nitrate. What are its reactions ? What is the arbor 
Dianm ? 



356 METALLIC ELEMENTS. 

ered it by the eye. It is also found alloyed with gold and 
silver in Brazil. It is a grayish-white metal, rather more 
brilliant than platinum, ductile, malleable, and extremely 
infusible. It is, however, fused by the compound blowpipe. 
It gains a blue tarnish like steel by heating in the air, which 
it loses by a white heat. In hardness it is equal to fine 
steel, and it does not lose its elasticity and stiffness by a red 
heat. Its density varies from 105 to 11*8, and it suffers no 
change by exposure in the air. These qualities would 
render it a very valuable metal if it could be obtained in a 
sufficient quantity. Nitric acid dissolves it slowly, but aqua 
regia more rapidly. It forms two oxyds and two corres- 
ponding chlorids. 

V. IRIDIUM. 

^ 665. Iridium is also associated with the ores of platinum 
in the native alloy called iridosmine, or osmiuret of iridium, 
which is left in black shining scales as a residuum, after 
digesting platinum ores in aqua regia. Iridium, when ob- 
tained pure and fused, is susceptible of a fine polish, has a 
pale antimonial whiteness and the fracture of cast-iron. 
It is somewhat ductile, as hard as unannealed steel, and fuses 
under the compound blowpipe. It is the densest of metals, 
being as high as 21-80. (Hare.) The native alloy is much 
more infusible than the pure iridium, being, in fact, one of 
the most infusible bodies known. The native alloy is also 
very hard, and is used to point gold pens. Four oxyds and 
four chlorids have been described. 

VI. RHODIUM. 

\666, This is another metal associated with the ores of 
platinum, and is obtained by a process which need not be 
described here. It is a reddish-white metal, at least as fusi- 
ble as iridium, and in hardness, ductility, and malleability, 
is much like it. Its density is probably about 10;8. (Hare.) 



§ 664. What is the symbol and equivalent of palladium ? Describe its 
properties. § 665. With what metals is iridium associated? What is 
its density and hardness? § 666. What is said of rhodium? 



PLATINUM. 357 



VII. PLATINUM. 



Equivalent, 98-68. Sy7nbol, PL Deiisiti/, 1970 to 21-23. 

^ 667. Platinum is a very remarkable metal, and if 
abundant would be extensively useful in domestic econ- 
omy. It is found native in the gold workings in South 
America and in Siberia, on the eastern slope of the Urals. 
No ore of platinum is known, except its alloy with gold, 
and with iridium, osmium, and rhodium. 

Platinum is a white metal between tin and steel in color, 
but harder than gold or silver, and unless quite pure is, when 
unannealed, nearly as hard as palladium. A very little rho- 
dium or iridium renders it more gray in color, and much 
harder. If pure it is very malleable, especially when hot, 
and can then be welded like iron. Its ductility is remark- 
able, as well as its tenacity. But its most valuable prop- 
erty is its infusibility, which is so great that the thinnest 
platinum foil may be safely exposed to the most intense 
heat of a wind-furnace. It is soluble only by aqua regia, 
but alloys readily with lead, iron, and other base metals, 
so that great care is needed in using platinum vessels, not 
to heat them in contact with any metal or metallic oxyd 
with which' they combine ; caustic potash also, and phos- 
phoric acid in contact with carbon, will act upon platinum, 
at a red heat. This is a most useful metal to the chem- 
ist, and quite indispensable in the operations of analysis. 
Large retorts or boilers are made of it for the use of manu- 
facturers of sulphuric acid, which sometimes hold sixty 
or more gallons. In Russia it has been employed in 
coinage, for which its great density and hardness are re- 
markably suited. When recently fused by the compound 
blowpipe or the galvanic focus, its density is about 19*9, 
which is increased to 21-5 by pressure and heat. 

§ 668. Platinum is obtained pure by digesting its ores 
in aqua regia, and adding to the deep brown liquid a solu- 
tion of chlorid of ammonium ; this throws an orange-colored 
precipitate, which is a double chlorid of platinum and am- 
monium. This precipitate is reduced by heat to the state 
of pure spungy platinum, — a porous dull brown mass, com- 

§667. Where is platinum found? Describe its characters and uses. 
§ 668. How is it obtained from its ores ? 



358 



METALLIC ELEMENTS. 



monly known as platinum spunge. All the platinum of com- 
merce is treated in this way. The spunge is condensed in 
steel moulds by heat and pressure, and when compact enough 
to bear the blows of the hammer, is heated and forged until 
it is perfectly tough and homogeneous. 

Spungy platinum is a very remarkable substance, having, 
as already noticed, (^ 396,) power to cause the combination 
of hydrogen and oxygen, and to affect other chemical changes 
without being itself altered. 

Platinum black is a still more curious form of metallic 
platinum, and may be easily formed by electrolyzing a weak 
solution of chlorid of platinum, when the black powder of 
platinum will appear on the negative electrode. The silver 
plates in Smee's battery (§ 246) are prepared in this way. 
It is also prepared by adding an excess of carbonate of 
soda, with sugar, to a solution of chlorid of platinum, and 
gradually heating the mixture to near 212°, stirring it mean- 
while. The black powder which falls is afterwards collect- 
ed and dried. This powder has the property of causing un» 
ion among gaseous bodies — as the elements of water — to a 
more remarkable degree than the spungy platinum. 

§ 669. Platinum forms two oxyds and two chlorids, viz : 
PtO, Pt02, and PtCle, PtCl2. The oxyds are prepared from 
the chlorids by alkalies, and are very unstable. The proto- 
chlorid is prepared by heating the bichlorid to 450°, when 
the protochlorid is left as a greenish-gray, insoluble powder. 

The bichlorid of platinum is the usual soluble form of 
platinum, and is always formed when platinum is digested 
in aqua regia. It is prepared pure by dissolving spungy 
platinum in this menstruum, and cautiously expelling the 
acid by evaporation, at a moderate temperature. It gives 
a rich orange solution both in alcohol and water ; and 
forms double salts of much interest, with many metallic 
chlorids. Those with the alkaline metals are the most im- 
portant. The double chlorid of platinum and potassium is 
a very sparingly soluble salt, (PlCl2,PCl,) which falls as a 
yellow highly crystalline precipitate when chlorid of plati- 
num is added to a solution of chlorid of potassium. The 
double chlorid of sodium and platinum (PtCl2NaCl+6HO) 



What is platinum black, and what are its properties ? § 669 How is 
the bichlorid prepared ? Describe the double chlorids of platinum and 
the alkalies, their preparation and characteristics. 



PLATINUM. 359 

is on the other hand very soluble, and forms large beautiful 
yellowish-red crystals in a dense solution. Potash and 
soda are most easily separated, by the different solubility of 
their double chlorids. The double chlorid of ammonium 
and platinum (PtCl2NH4Cl) is the orange precipitate before 
named, and is the only test required to determine with per- 
fect certainty the presence of platinum in a solution. 



PART IV.— ORGANIC CHEMISTRY. 

I. INTRODUCTION, 

1 . General Properties of Organic Bodies, 

§ 670. Definition. — Organic chemistry is confined to the 
study of those bodies which are the products of life, and to 
the changes which they suffer by the action of other sub- 
stances. 

^ 671. The constituents of organic bodies are compara- 
tively few, but the results produced by their various combi- 
nations are wonderfully complex and numerous. Oxygen, 
nitrogen, carbon, and hydrogen, differently arranged and 
combined, compose nearly all the bodies found in the vege- 
table and animal kingdoms. Sulphur, phosphorus, and per- 
haps iron, occasionally occur, however, in these products ; 
and by the action of various reagents we are enabled to 
combine with organic compounds, or with the products of 
their decomposition, chlorine, bromine, iodine, and various 
other bodies. In this way a great number of new com- 
pounds are produced, which come within the province of or- 
ganic chemistry as above defined. 

^ 672. Both animals and vegetables contain salts of pot- 
ash, soda, lime, magnesia, and iron, with sulphuric, phos- 
phoric, silicic acids, and chlorine. Animals also secrete 
phosphate and carbonate of lime, to form their bones, as in 
quadrupeds, and their external coverings, as in the mollusca. 
These salts have been already described under their proper 
heads, in the inorganic chemistry, and their relations to life 
will be considered in the section on the nutrition of animals 
and plants. 

^ 673. A strictly philosophical distinction cannot be es- 
tablished between organic and inorganic chemistry, as it 
will be seen from the statements already made, that these 
two departments shade into each other so gradually, that 
the line of division must of necessity be somewhat arbitrary. 

§670. Define organic chemistry. § 671. What is said of the constit- 
uents of organic bodies? What elements enter into their combination? 
§ 672. What is said of some other secretions of the vital organism ? 



GENERAL PROPERTIES OF ORGANIC BODIES. 361 

Formerly it was considered as a distinctive mark of or- 
ganic compounds, that they could not be artificially formed 
at will, from a combination of their constituents. This 
distinction is, however, no longer exclusively true, since 
we are now able to form urea from cyanic acid and ammo- 
nia, both of which may be derived from the reaction of the 
mineral ingredients. By peculiar processes we have also 
been able to form numerous other bodies which are the 
products of organic life.* They are, however, compara- 
tively simple in their composition, and occur in nature only 
as secretions of organized bodies.f No art can ever enable 
us to produce the simplest organized tissue, as a cell or a 
fibre. 

^ 674. An important characteristic of organized bodies is 
the complexity of their composition, and their high equiv- 
alent numbers. In mineral compounds we rarely have any 
thing more intricate than a salt of two or three bases ; as for 
example, common alum, (§ 576,) which may be resolved into 
the binary compounds, sulphuric acid, alumina, potash, and 
water, each of which contains oxygen and a base. These 
constituents may be again combined to form the original 
alum. 

§ 675. The substance called[|elatine^vrhich is a principal 
constituent of the cellular tissue in animals, has the formula 
C^gH^jN^O^g- By the action of heat, or other agents, 
we are able to resolve this complex body into ammonia, 
water, and other compounds, which are very much more sim- 
ple than gelatine. And these again, we may decompose 
into their constituent elements. But by no power at our 
command, can we join the dissevered elements to form ge- 
latine anew. This peculiarity of organization is dependent 
on the vital force, which modifies the chemical affinities of 

§ 673. What is said of the artificial formation of organic products? 
What is the distinction between an organized and an organic body ? Note. 
Can we ever hope to produce artificially any organized substances? 
§ 674. What peculiarity of organic bodies is here mentioned? § 675. Il- 
lustrate this by alum and gelatine. On what force is this arrangement 
dependent ? 

* E. g. Allantoin, the oils of spirea ulmaria, wintergreen, &c 
t Organized bodies, or organisms, are distinguished by having a 
structure, which is the result of life ; this organic bodies do not neces- 
sarily possess For example, horn and skin are organisms, while gum 
and fat are simply organic bodies. 

31 



362 ORGANIC CHEMISTRY. 

bodies, in a manner that we can never hope to imitate. 
While, therefore, in the study of mineral chemistry we can 
usually avail ourselves of the evidence to be obtained from 
both analysis and synthesis, (^ 14,) in organic chemistry 
we must generally be content with the former of these 
methods of proof. 

§ 676. Organic bodies possess the further peculiarity, 
that carbon is almost invariably one of their constitu- 
ents, and associated in such proportions with oxygen, nitro- 
gen, and hydrogen, that when the body is burned, these last 
combine with it to form carbonic acid and carbureted hydro- 
gen ; and also among themselves, producing water and am- 
monia ; while any excess of carbon remains behind as char- 
coal. Organic bodies have for this reason been defined by 
some writers as those bodies which char or blacken by 
heat. 

2. Compound Radicals, 

§ 677. The elements of inorganic bodies manifest a ten- 
dency to unite with each other in the form of binary or other 
simple combinations, which is also strikingly exhibited in 
organic substances. Thus, for example, sulphur and potas- 
sium both unite with oxygen, forming sulphuric acid and 
potash, and these two binary compounds again unite to 
form sulphate of potash. In the organic kingdom we find 
many analogous cases in which compound bodies unite with 
each other and with elements, in the same manner as if 
they were themselves elementary. Such bodies are called 
compound radicals. 

§ 678. These compound radicals appear to exist in a very 
large number of substances, and they furnish us the best 
means we possess of classifying and bringing into systematic 
order, the numerous facts of organic chemistry. Our knowl- 
edge is yet too imperfect to enable us to form on this basis 
a complete system of classification. So far as it extends, 
however, it seems most elegant and philosophical, and is 
in accordance with the system on which we arrange the 
chemistry of inorganic bodies. 

§ 679. Definition, — A compound radical is then a body 

§ 676. What other characteristic of these compounds is mentioned ? 
§ 677. What is a compound radical? § 679. To what are the first class 
of these bodies related ? Give examples. 



COMPOUND RADICALS. 



363 



which although composed of two or more simple bodies, per- 
forms in combination the part of an element, (^ 293, ^ 486.) 
Thus we find a class of compound radicals, of which cyan- 
ogen may stand as the representative, performing functions 
precisely analogous to chlorine, and the hypothetical radical 
of sulphuric acid, oxysulphion, SO^. This will be more 
evident from a comparison of the formulas of a few of their 
compounds. 



Radicals. 



Acid with 
Hydrogen. 



Potassium 
Salt. 



Silver 
Salt, 



Chlorine = CI, 
Oxysulphion = SO4 , 
Cyanogen = CoN=Cy, 
Salicyle=C,4H5 =Sa, 



H+Cl 



H- 



H- 



■SO. 



H+Cy 



-Sa 



"CI 
SO 4 
-Cy 

-Sa 



Ag+Cl 
Ag+S04 
Ag+Cy 
Ag+Sa 



^ 680. A second group of compound radicals may be dis- 
tinguished, which seem analogous to carbon or sulphur ; 
they form, with oxygen, compounds which act like the 
radical SO^. Thus oxalyle, C2O2, combines with oxygen 
to form oxalic acid, and with chlorine to form chlorid of 
oxalyle, (CgO^ CI,) or phosgene gas, (§ 348 ;) presenting thus 
an analogy to sulphur, which forms in the same manner sul- 
phuric acid and chlorid of sulphur. 

^681. A third class of radicals seems closely allied to 
the metals ; they yield with oxygen compounds whose basic 
properties resemble those of the metallic oxyds, and com- 
bine like them with chlorine, bromine, and sulphur, to form 
compounds similar to those of the metals with the same rad- 
icals. Ethyle, C4H5, (the radical of ether,) and kakodyle, 
C4HgAs2, are examples of this class. 

^ 682. A fourth class of radicals embraces some com- 
pounds which partake of the properties of both the prece- 
ding groups. Like oxalyle they form acids with oxygen, but 
yield with chlorine, sulphur, cyanogen, &c., compounds 
closely allied to those formed in the last group. 

^ 683, These radicals are generally unknown in a sepa- 
rate state, and can be studied only in combination. Thus 
we do not know ethyle in a separate or uncombined form, 



§ 680. Describe the second group, and give an example. § 681. What 
are the characteristics of the third group? § 682. To what is the fourth 
closely allied? § 683. Can these bodies be isolated? What is our evi- 
dence of their existence? On what ground rests our evidence of the ele- 
mentary character of chlorine and zinc ? 



364 ORGANIC CHEMISTRY. 

as we know zinc or hydrogen. Yet we can combine it with 
chlorine, iodine, sulphur, and oxygen ; and its oxyd with ni- 
tric, sulphuric, and other acids. Indeed, so closely allied 
is it in all its reactions to an element, that were we not 
able to decompose it, the strictest rules of chemical rea- 
soning would compel us to admit its elementary character. 
We must never forget that the evidence in favor of the ele- 
mentary character of any one of our admitted elements is 
only negative, and we cannot safely affirm that many of them 
may not yet be resolved into simpler forms. 

3. Theory of Types and Substitutions. 

§ 684. When the organic compound called naphthaline 
(C20H3) is exposed to the action of chlorine gas, we find 
that the hydrogen in its composition may be wholly or in 
part replaced by the chlorine. Thus we may, according to 
the extent of the action, form either C^oH^Cl, or C2oCIg. 
In these new bodies the general arrangement of the atoms 
seems unchanged ; the twenty equivalents of carbon still 
remain, whatever changes or substitutions of the hydrogen 
may take place. 

If we subject acetic acid (C4H3O3HO) in the same man- 
ner to the action of chlorine, we obtain a new compound, the 
chloracetic acid =z C4CI3O3, HO, in which three atoms of 
hydrogen have been replaced by a like number of chlorine. 
The new compound has a very close resemblance in all its 
properties to acetic acid, and we are therefore led to believe 
that in both the arrangement of the atoms is exactly similar. 
It is in fact acetic acid in which chlorine is substituted for 
hydrogen. 

§ 685. In theory we may form a series of acids in which 
bromine and iodine shall in the same manner take the 
place of hydrogen. A general expression for the constitu- 
tion of these acids will then be C4X3O3, HO, in which 
body X represents chlorine, bromine, iodine, or any other 
which is capable of replacing the hydrogen. The ex- 
pression is called the type of acetic acid. 

This view of the constitution of ororanic bodies leads us 



§ 684. How does chlorine act on naphthaline ? How on acetic acid ? 
§ 685. What formula will express the composition of the bodies derived 
from acetic acid by substitution ? 



THEORY OF TYPES AND SUBSTITUTIONS. 365 

to these important generalizations : (1,) That a compound 
may be considered as a group of atoms acting in relation to 
other bodies as a single atom. (2.) That any number of the 
atoms of one kind in a compound may be replaced (substi- 
tuted) by the same number of atoms of another element, 
which coincides with them in power. (3.) The constitution 
of the body may remain unchanged, while its chemical 
characteristics are, to a greater or less extent, altered. 

§ 686. If we view the elements of naphthaline (C^qH^) 
as arranged in such a group, we can conceive that different 
atoms of hydrogen sustain different relations to the whole 
mass, and consequently if we can replace at will, one, two, 
or more of them, by the like number of atoms of chlorine, we 
shall obtain a series of bodies having different properties. 
Such results have actually been obtained by M. Laurent in 
his very interesting researches on the naphthaline com- 
pounds. 

Two compounds have been described by him, both of 
which contain C2oH4Cl3Br. But both of these com- 
pounds have very distinct properties, and in the mode 
of their formation there is sufficient evidence of a difference 
of arrangement of the atoms. One of them may perhaps be 
C20H4CI3, Br, and the other C^oH^Br, Cl^. 

4. Allotropism of Elements in Organic Compounds. 
4 687. In the chloracetic acid we observe the remark- 
able fact that chlorine, a strongly electro-negative ele- 
ment, replaces hydrogen, which is as decidedly an elec- 
tro-positive Hody. This apparently anomalous fact was 
not well understood until Dr. Draper, in his researches on 
the allotropic state of chlorine, (^ 263) demonstrated that 
this element can exist in a state in which it is completely 
indifferent to hydrogen, although its affinity for this body 
under ordinary circumstances is one of the most powerful 
with which we are acquainted. Chlorine can apparently 
put on an electro-positive condition, and it is probable that it 
enters into the condition of organic bodies, as in chloracetic 
acid and the chloronaphthaline series, while in this allotropic 
condition. The same remark is, by inference, true of bro- 

What is the general expression called ? What conchision may we 
draw from these facts— (1) ? (2)? (3)? §686. What illustration is 
given of these cases ? § 687. How can we explain the fact that chlorine 
replaces hydrogen ? 

31* 



366 



ORGANIC CHEMISTRY. 



mine and iodine and other electro-negative bodies which act 
in organic compounds a similar part. 

5. Isomerism. 

^ 688. Organic compounds which are identical in the rel- 
ative number and proportion of their constituent atoms, are 
not necessarily identical in their physical properties. Urea 
and cyanate of ammonia contain precisely the same number of 
equivalents of each element, namely, CgNgH^O^ ; yet 
these bodies are very different from each other in their prop- 
erties. This must depend on a different arrangment of the 
molecules in the compound by which the complex molecule 
is endowed with entirely different affinities. Such bodies 
are distinguished by the term isomeric J*" The naphthaline 
compounds just mentioned offer us fine examples in illus- 
tration of this difference of arrangement among constituent 
molecules, to which is attributable the remarkable diversity 
of properties among bodies composed of the same proportions 
of the same elements. 

§ 689. Another class of compounds analogous to the last 
may be illustrated by alcohol and methylic ether. The com- 
position of these bodies in 100 parts is the same, but the 
equivalent of the former is twice that of the latter compound. 
This is best seen by reference to their formulas : 
Alcohol r=: C4H4, 2H0, 

Methylic ether =: C2H2, HO. 

Many remarkable instances of this kind are presented to 
us in the compounds of carbon and hydrogen. For ex- 
ample, we may mention 

Equivalents. Combining measures. 

defiant gas, C^H^ 4 volumes. 

Oil gas, C3H3 4 " 

Cetene, C32H33 4 " 

In these compounds the relative number of equivalents is 
the same, as well as the combining measures or volumes of 
their vapors. Consequently in cetene the constituents are con- 

§ 688. Does identity in the proportions of the same elements imply sim- 
ilarity in composition? What illustrations are given of this truth ? §689. 
How do alcohol and methylic ether differ? 

* From iso8, equal, and meros^ measure. 



DECOMPOSITION OF ORGANIC COMPOUNDS. 367 

densed eight times more than in olefiant gas, from which re- 
suits a difference of properties. Bodies, which like the^p 
differ in the absolute number of their atoms, are denominated 
poly ineric bodies ; while those in which a different arrangement 
exists, as in urea and cyanate of ammonia, are called 
metameric bodies ; and those in which the absolute number 
of atoms, and consequently their arrangement, is unknown, 
are called simply isomeric, 

6. Decomposition of Organic Compounds, 

^ 690. Organic compounds when removed from the influ- 
ence of vitality and exposed to the action of the air, display 
a remarkable disposition to suffer change and decomposition, 
the result of which is to resolve them into simpler pro- 
ducts. The expressed juice of the grape does not ferment 
until it has been brought into contact with atmospheric air, 
when the oxygen immediately commences a change in it, 
that, once begun, continues, even if further excess of 
air is excluded, until all the sugar in the juice is resolved 
into alcohol and carbonic acid. This singular transforma- 
tion will happen in a solution of pure sugar shut out from 
all access of air, provided we add to it a little of the grape- 
juice, or of any other body previously in this state of change. 
This communicates its own condition to the solution of sugar, 
which is at length completely resolved into carbonic acid 
and alcohol. 

§ 691. The most probable explanation of this class of 
phenomena is; that a body in a state of change has the 
power, by simple contact, of inducing a change in other bodies 
previously in a state of rest. The well known law of me- 
chanics, that a body in motion can impart its own motion to 
other bodies previously at rest, will perhaps serve to give us 
an imperfect idea of the theory of contact. Our knowledge 
of the nature of molecular actions is very limited ; but we may 
perhaps acquire a more definite idea of this theory of fer- 
mentation, by extending the mechanical law just cited, from 
masses to atoms, and from sensible mechanical motion, to 
the motions which may be supposed to take place among 

What are polymeric bodies? Give an example. What are meant by 
metameric and isomeric substances? § 690. What is said of the tendency 
of organic bodies to chanjre? Describe the fermentation of sugar. 
§ 691. How is this explained? 



368 ORGANIC CHEMISTRY. 

the combining molecules. This process is not really differ- 
est from that by which a body in a state of combustion 
(^ 460) can set fire to other substances with which it is 
brought in contact. In this case, the state of motion among 
the particles makes itself evident to our senses by commu- 
nicating that state to our own bodies ; while in fermenta- 
tion, the motion is one that is necessarily confined within 
the limits of the decomposing substances. 

§ 692. We find in chemistry many cases which illustrate 
this view. Thus, when oxyd of silver is added to a weak 
solution of peroxyd of hydrogen, (§ 410,) the latter is immedi- 
ately decomposed with escape of oxygen gas, and the oxyd 
of silver receiving from the decomposing liquid its peculiar 
state or kind of motion, is itself decomposed into oxygen 
and metallic silver. This decomposition is quite contrary 
to our usual experience, since we should hardly look 
for the reduction of an oxyd by the decomposition of a highly 
oxydized body. Platinum is quite insoluble in nitric acid ; 
but if alloyed with silver, the compound is readily dissolved 
in this acid. Here the silver in the act of combination com- 
municates its own state to the particles of platinum with 
which it is in contact, and they are at once oxydized and 
dissolved. This beautiful theory was first applied to chem- 
ical action by Liebig, and has enabled us to explain in a 
satisfactory manner many phenomena hitherto very imper- 
fectly understood. 

The action of acids and various other agents on organic 
substances, must (from our limited space) be considered in 
connection with the substances themselves. 

II. ANALYSIS OF ORGANIC SUBSTANCES. 

§ 693. The ultimate analysis of organic substances is of 
great importance ; for as we are unable to form them by a di- 
rect combination of their elements, a correct understanding 
of their composition and of the nature of the changes which 
they undergo, must depend entirely on the results of their 
analysis. In the complex products of organic life, the 
equivalent is often so large, that a change of one hundredth 
part in the proportions, gives to the compound entirely 

Illustrate it by meehanical motion. By combustion. § 692. What is 
mid of the action of silver on peroxyd of hydrogen 1 



ANALYSIS OF ORGANIC SUBSTANCES. 369 

distinct properties. Great refinement is consequently neces- 
sary in analysis, to enable us to detect the minute differences 
in composition, and such have been the care and skill with 
which the subject has been studied, that we have now ar- 
rived at a surprising accuracy in operations of this kind. 

^ 694. In theory, the process of orsjanic analysis is ex- 
ceedingly simple. If any organic substance, as sugar, for ex- 
ample, is heated with a body capable of yielding oxygen, such 
as the oxyd of copper, lead, or any other easily reducible met- 
al, it is completely decomposed ; the carbon and hydrogen take 
oxygen from the metallic oxyd, and are wholly converted 
into carbonic acid and water. From the weight of these, it is 
easy to calculate the amount of carbon and hydrogen in the 
body, and if it contains no other element except oxygen, 
this is known by the loss. But notwithstanding the the- 
oretical simplicity of the process, its execution is exceed- 
ingly difficult, and very many precautions are necessary 
to ensure accuracy. It is not the object of this work to ex- 
plain all the cautions necessary to the successful perform- 
ance of analytical operations, but merely to give an outline of 
the method pursued, and a general idea of the means em- 
ployed. For more particular information the student is re- 
ferred to an excellent memoir on this subject, by Baron 
Liebig. 

^ 695. The operation is performed in a combustion tube of 
hard glass, about 12 inches in length, and from -^^ to -f^ of 
an inch in diameter. One end is drawn out to a point, turned 
aside and sealed. Oxyd of copper prepared from the nicrate 
(^ 616) is generally employed for the combustion. Just before 
using it, it is heated to redness, in order to expel the moist- 
ure which it readily attracts from the atmosphere ; the com- 
bustion tube is then about two-thirds filled with the hot oxyd. 
The substance to be analyzed having been carefully desi- 




Oxyd. ]^Iixture. Oxyd. 



§694. What is the theory of organic analysis? §695. Describe the 
combustion tube. Describe tha mode of using the oxyd of copper. 



370 



ORGANIC CHEMISTRY. 



cated, 5 or 6 grains of it are weighed out in a tube with a 
narrow mouth, in order to prevent the absorption of moisture. 
It is then rapidly mixed in a dry porcelain mortar, with the 
greater portion of the oxyd from the tube, to which it is 
again transferred, and the tube is then nearly filled up with 
pure oxyd. The relative portions of the oxyd and mixture 
are shown in the figure on the previous page. 

^ 696. However carefully the mixture has been made, a 
little moisture will be absorbed, which must be removed 
by the following arrangement. To the end of the com- 
bustion tube is fitted, by means of a cork, a long tube 
filled with chlorid of calcium, and to this is attached a small 
air pump. The combustion tube is covered with hot sand, 
and the air slowly exhausted. After a short time, the stop- 




cock is opened, and the air allowed to enter, thoroughly 
dried by its passage over the chlorid of calcium. It is 
again exhausted, and this process repeated four or five times, 
by which the mixture is completely dried. The annexed 
figure shows the arrangement for this purpose. 

§ 697. The tube is now ready for the combustion, and is 

I placed in the 

^1 furnace repre- 
sented in the 




accompanying 
figure. It is 
constructed of sheet iron, and fitted with a series of supporters 



§ 696. How is the moisture removed? §697. Describe the furnace. 



ANALYSIS OF ORGANIC SUBSTANCES. 



371 



at short distances from each other, to prevent the tube from 
bending when softened by heat. The furnace is placed on 
a flat slone or tile, with the front slightly inclined down- 
wards. The quantity of water formed in the process is es- 
timated by a light tube, rep- r——m ^.,,.,mm4J^^m^^^^^^ r—~ 
resented in the annexed ^ ^^^^^ 

figure, which is filled with fragments of chlorid of cal- 
cium, and after having been very carefully weighed, is at- 
tached by a well dried and closely fitted cork, to the end of 
the combustion tube. To determine the carbonic acid, a 
small five bulbed tube of peculiar form, called 
Liebig's potash bulb, and represented in the 
annexed figure, is used. It is charged for 
this purpose with a solution of caustic potash 
of a specific gravity about 1-25, with which 
the three lower bulbs are nearly filled. Its 
weight is determined with great exactness, 
and it is then attached to the chlorid of cal- 
cium tube, by a little tube of gum elastic, 
which is held fast by a silken cord. The whole arrange- 
ment is shown below. The tightness of the junction is 





ascertained by drawing a few bubbles of air through the 
end of the potash tube, so that the liquid will be raised a 
few inches above the level on the other side ; if this level 
remains the same for some minutes, the whole apparatus is 
tight. 

§ 698. Heat is now applied by means of ignited charcoal 
placed around the anterior portion of the tube, and when 
this is red-hot, the fire is gradually extended along the tube, 



How is the water collected? The carbonic acid? § 698. How is the 
heat applied? From what is the amount of liydrogen and carbon deter- 
mined ? 



372 



METALLIC ELEMENTS. 



by means of a moveable screen, represented in the figure. 
This must be done so slowly as to keep a moderate and uni- 
form flow of gas through the potash solution. When 
the whole tube is ignited, and gas no longer escapes, the 
closed end of the combustion lube is broken off, and a 
little air drawn through the apparatus to remove all the re- 
maining products of combustion. The tubes are then de- 
tached, and from the increase of weight in the chlorid of 
calcium tube, the amount of water, and hence that of hydro- 
gen, is deduced. The carbon is determined from the in- 
crease in weight of the potash bulbs, by a simple calcula- 
tion. 

^ 699. Volatile fluids are analyzed by enclosing them in 
a narrow necked bulb of thin glass, tilled with the fluid in the 
same mode as thermometers, (§ 76.) 
The weight of the empty tube is first 
ascertained ; the fluid is introduced, 
the neck sealed, the weight being 
again ascertained, and the difference 
gives the weight of the fluid. The 
neck of the bulb is then broken by a 
file mark {a) dropped into the closed 
end of the combustion tube, and cov- 
ered with oxyd of copper, which should nearly fill the tube. 
When this is heated to redness, a gentle heat applied to the 
portion of the combustion tube containing the volatile fluid, 
sends it in vapor over the ignited oxyd, completely burn- 
ing it. The products of its combustion are estimated as 
as before. 

§ 700. Fatty bodies and others which contain much car- 
bon and a small quantity of hydrogen, are more perfectly 
burned by employing chromale of lead in place of the 
oxyd of copper. This substance does not readily attract 
moisture from the atmosphere, like oxyd of copper, and is 
consequently better when the hydrogen is to be determined 
accurately. The chromate of lead (§ 609) is prepared for 
use by heating it until it begins to fuse, and when cool, re- 
ducing it to powder. 

§ 701. When nitrogen is a constituent of organic bodies^ 
it is determined by placing in one end of the combustion 

§ 699. How are volatile fluids analyzed? §700. For what purposes is 
chromate of lead employed ? 




ANALYSIS OF ORGANIC SUBSTANCES. 373 

tube, about three inches of carbonate of copper, secured in 
its place by a plug of asbestus ; and then the nitrogenous 
body is introduced, mixed with oxyd of copper. The re- 
maining space in the combustion tube is filled with turnings 
of metallic copper. The air is then withdrawn by an air- 
pump, and a gentle heat applied to the carbonate of cop- 
per, which evolves carbonic acid, and drives out all remain- 
ing traces of common air. The tube is now heated as usu- 
al, and the gases evolved are collected in a graduated air- 
jar, over mercury. When the combustion is finished, heat 
is again applied to the carbonate of copper, and another 
portion of carbonic acid expelled, which drives out all the 
nitrogen from the tube. The use of the copper-turnings is 
to decompose any traces of nitric oxyd, which may be form- 
ed in the process. The carbonic acid is removed from the 
air-jar, by a strong solution of potash, and pure nitrogen 
remains, which is measured with the usual precautions, and 
from its volume the weight is easily determined. 

§ 702. Another and a preferable mode of determining nitro- 
gen, is that of Will and Yarrentrapp, which is founded on 
the fact that when a body containing nitrogen is heated with 
an excess of caustic potash, or soda, all the nitrogen is evol- 
ved in the form of ammonia, and may be thus estimated. 

§ 703. Chlorine is determined in the analysis of organic 
compounds, by passing the vapor over quick-lime heated to 
redness in a combustion tube ; chlorid of calcium is formed, 
which is afterward dissolved in w^ater, and the chlorine pre- 
cipitated by nitrate of silver. From the weight of the chlo- 
rid of silver, the amount of chlorine is calculated. 

§ 704. Sulphur is a rare constituent of organic com- 
pounds. Its presence is detected by fusion with nitre and 
carbonate of soda, or by digestion with nitric acid. Sul- 
phuric acid is thus formed, and is precipitated as sulphate 
of baryta, from the weight of which, that of the sulphur is 
determined. In the analysis with oxyd of copper, a small 
tube of peroxyd of lead is introduced between the chlorid 
of calcium tul3e and the potash apparatus, to absorb the sul- 
phurous acid which is evolved. 



§ 701. How is nitrogen estimated? § 702. On what does the process 
of Will and Varrentrapp depend? § 703. How is chlorine determined ? 
§ 704. By what means is the presence of sulphm* detected ? 

32 



374 ORGANIC CHEMISTRY. 

IL COMPOUND RADICALS. 

I. AMIDE OR AMMIDOGEN,* NHj. 

Symbol, Ad. Equivalent, 16*19, 

^ 705. Ammidogen ha8 already been mentioned (^ 445-) 
as the probable base of the ammonia compounds. When 
potassium is heated in dry ammoniacal gas, hydrogen is 
evolved, and an olive-green mass is formed, which is found 
to have the composition KNHg, or KAd, analogous in con- 
stitution to the chlorid of potassium, (KCl.) When this 
compound is put into water, ammonia is evolved, and 
caustic potash remains in solution, KAd-i-HO = KO + AdH 
or NH3. Again, when oxalate of ammonia (NH^O, €30^) 
is heated, it is decomposed, forming water, and a substance 
having the formula, NH2C2^2- '^^^^ ^^ called ox amide ; 
it is a neutral, insoluble body, and contains neither ammonia 
nor oxalic acid. In contact with an alkali or acid, it takes 
up the elements of water, and is converted into oxalate of 
ammonia, (NH2C202 + 3HO=:NH40, C2O3.) A similar 
transformation takes place with the ammoniacal salts of a 
number of vegetable acids, giving rise to bodies having a 
general resemblance to oxamide, which have received the 
name of amides or ammidids. 

Compounds of Ammidogen with Hydrogen, 

§ 706. Ammidogen combines with hydrogen in two propor- 
tions, to form ammonia (AdH) and ammonium, (AdH2,) of 
which the first is a simple ammidid, and the second a subam- 
midid. The general properties of these bodies have been al- 
ready presented, (^ 440, ^ 444, and § 541.) 

Ammonia is evolved in large quantities by the decompo- 



§ 705. What is the composition of ammidogen ? How does potassium 
act upon ammonia ? What is said of the nature and properties of ox- 
amide? § 706. What is the composition of ammonia? How is it gen- 
erated ? 



* This term being derived from ammonia^ is more properly spelt with 
a double m, than with one, eis is the usual custom. 



OXYD OF CARBON. 



?75 



sition of all organic substances which contain nitrogen ; its 
elements have a strong affinity for each other, and in these 
reactions are brought together, in such a manner that they 
combine and produce ammonia. 

^ 707. Ammonia is abundantly absorbed by many salts, 
and appears to perform a function analogous to that of 
water of crystallization. With some of the metallic salts, 
the action is less simple ; chlorid of mercury, for example, 
is decomposed to form an ammidid, HgCl-f AdH^HgAd-j- 
HCl. The ammidid combines with an equivalent of the chlo- 
rid to form ^. chlor ammidid of mercury, HgCl, HgAd, (§ 658.) 
Ammonia with chlorine, iodine, and bromine, forms a series 
of substances which have been considered as combinations 
with nitrogen, but they really contain hydrogen, and are 
probably compounds of ammidogen. 

§ 708. Chlorid of Ammidogen, KAC\^\^.']— Chlorid of Ni- 
trogen. — When a jar of chlorine gas is inverted over a solutioa 
of an ammoniacal salt, the chlorine is absorbed, and a heavy 
oily fluid separates, which is the new compound. It is most 
dangerously explosive, and great care should be taken in 
experimenting with it. A gentle heat, the contact of any fat 
oil, or phosphorus, causes it to decompose with a violent 
detonation. lodid of Ammidogen, Adl2, [?] is formed when 
ammonia acts on iodine. It is a black povi^der, which de- 
tonates with the least friction or slight warmth, but much 
less violently than the chlorid. 

II. OXYD OF CARBON (oXALYLE*) =: C2O2. 

Equivalent, 28- 106. 

§ 709. The oxyd of carbon appears in many cases to act 
as a simple body or radical. It combines with chlorine, as 
has been already described, (§ 450,) to form phosgene gas, 
or chlorocarbonic acid. When potassium is heated in car- 
bonic oxyd, the bodies unite, and a black mass results, which 

§ 707. How does it act with many salts ? What is its reaction with 
chlorid of mercury? § 708. How is chlorid of ammidogen obtained? 
What are its properties? § 709. What are the reactions of oxyd of car- 
bon? What name applied to it, and why? 

* Because it is the base of oxalic acid ; the termination yle or ule, 
is from the Greek hule, matter or principle, and is the usual terminaiioii 
of organic radicals. 



370 ORGANIC CHEMISTRY. 

contain the elements of carbonic oxyd combined with potas- 
sium. To this radical, regarded either as CO or C2O2, the 
name of oxalyle has been given. 

1. Oxalyle with Oocy gen. 

§ 710. Oxalic Acid, C2O3, HO = (C202) O, HO.— This 
acid exists in many vegetables, and is the cause of the agree- 
able sour taste of the wood-sorrel, oxalis acetosella, and other 
plants of the same genus. It is, however, more easily ob- 
tained by the oxydation of sugar or starch. 

To prepare it, 1 part of starch is mixed with 8 parts of 
nitric acid, specific gravity, 1-25, and the mixture gently 
heated. A violent action ensues, and much nitric oxyd gas 
is evolved, from the decomposition of the acid ; when this 
ceases, the solution is concentrated by evaporation, and on 
cooling, yields a large quantity of crystals of oxalic acid, 
which are purified by washing in water, and recrystalliza- 
tion. 

§ 711. As thus obtained, oxalic acid is colorless, readily 
soluble in water, has a powerful acid taste, and is very poi- 
sonous. Its crystals are derived from the monoclinate sys- 
tem, (^ 222 ;) they contain 3 equivalents of water. By a 
gentle heat, two of these may be expelled, but the third is 
essential to the existence of the acid, and can be removed 
only by substituting in its place a metallic oxyd, or in other 
words, by substituting a metal for the hydrogen. The dry 
acid is sublimed by heat, and condenses unchanged. 

§ 712. When heated with sulphuric acid, it loses the ele- 
ments of an equivalent of water, and is resolved into a mix- 
ture of equal parts of carbonic acid and carbonic oxyd, CgOg 
= 002 + 00, (§ 346.) The same decomposition takes 
place, when some of its salts are heated ; as for example, the 
oxalate of manganese, MnO, C2O3, which affords MnO + 
CO2 + CO. But if the metallic oxyd is easily reduced, 
the only product is carbonic acid. Thus AgO, 0203= Ag 
+ 2OO2. Oxalic acid is largely employed in the arts of 
dyeing and calico printing. It is also used to clean metals, 
and remove iron-stains from linen, which it effects, by form- 
ing a soluble salt with the iron. 

§ 710. Does oxalic acid exist in nature? How js it prepared? § 711. 
What are its characters? § 712. How do its salts act when heated? 
What uses are made of oxalic acid ? 



CYANOGEN. 377 



2. Saks of Oxalic Acid. 

^ 713. This acid combines with bases, forming a large 
number of well characterized salts. It unites with potash 
in three portions, forming the following compounds : 

Neutral oxalate = KO, C2 O3+HO. 

Binoxalate = KO, C2 OgJIO, C2 O3+2HO. 

Quadroxalate = KO, C2 03,3(HO, C203)-|-4Aq. 

The oxalate of ammonia, NH^O, C2O3 + HO, crystallizes 
beautifully, and is much used in analytical chemistry to pre- 
cipitate lime ; when heated, it is in part decomposed into 
water and oxamide ; this compound may be considered as 
an ammidid of oxalyle, C2O2, Ad. 

^714. The oxalate of lime, C^0,C20 2 + ^ AqA^ a very in- 
soluble salt, and occupies an important part in the vegetable 
economy, being secreted by a large number of 
plants, in the cells of which, the microscope re- 
veals to us a great number of beautiful crystals 
of this substance ; as may be observed in the 
annexed figure of a vessel from the bark of 
Torreya taxifolia* In many of the lichens, the 
oxalate of lime appears to replace the woody 
fibre, and to be somewhat allied in its func- , 
lions to the carbonates and phosphates of lime 
in the animal kingdom. The oxalates of the metals are 
generally insoluble. 

III. CYANOGEN. t 

Symbol, C2N, or Cy. Equivalent, 26 23. 
§ 715. This body, which was discovered by Gay Lussac, 
is, in all its relations, one of the most important substances 
which science has made known to us. Although a com- 
pound, it comports itself exactly like an element, and enters 
into combination with metals, precisely like chlorine, iodine 

§ 713. Describe the oxalates of potash. What is the composition of ox- 
alate of ammonia'? What is the probable composition of oxamide? 
§ 714. What is said of oxalate of lime? § 715. What are the characters 
of cyanogen ? 

* Prof. J. W. Bailey, Am. Jour. Science, vol. xlvii, p. 17. 
t From kuanosj blue, and gennao, I form. 
32* 




378 ORGANIC CHEMISTRY. 

and sulphur. Cyanogen is obtained by heating cyanid of 
mercury in a glass retort, when it is resolved into metallic 
mercury and cyanogen gas, which must be collected over 
mercury. A more convenient process is to heat two parts 
of the ferrocyanid of potassium, and one of chlorid of mer- 
cury ; chlorid of potassium and cyanid of mercury are formed, 
which last is immediately decomposed by the heat. 

§ 716. Properties. — It is a colorless gas, readily soluble 
in water and alcohol, with a peculiar penetrating odor, hav- 
ing, when very much diluted with air, a resemblance to the 
perfume of peach blossoms. It burns in the air with a beau- 
tiful purple flame, yielding nitrogen and carbonic acid gases. 
Its specific gravity is 1-806, and it is reduced to a liquid by 
a pressure of four atmospheres. Cyanogen is formed when 
potassium is heated wath azotized matters, and generally 
when carbon and nitrogen are brought, at a red heat, into 
contact with an alkali. If ammonia is passed over a mix- 
ture of charcoal and carbonate of potash, cyanogen is pro- 
duced, and combines with the potash to form cyanid of 
potassium ; and the same result is obtained if common air 
or nitrogen is substituted for ammonia, provided the heat 
is intense. 

§ 717. A small quantity of a brownish-black, insoluble 
matter remains in the retort, after decomposing the cyanid 
of mercury, which is apparently isomeric with cyanogen, 
and has been called paracyanogen. Cyanogen and all its 
compounds are procured from the cyanid of potassium, 
formed by the action of alkalies on animal matters. The 
cyanid of potassium is obtained from the incinerated mass 
by solution, and is then digested with a salt of iron, by which 
a new salt is formed, which is a compound of cyanid of 
potassium and cyanid of iron. This salt crystallizes in large 
yellow tables, and is well known in the arts as the yellow 
prussiate of potash^ or more properly, ferrocyanid of potas- 
sium. Its composition may be represented by the following 
formula: FeCy,2KCy + 3HO. From this, we can easily 
obtain all the other compounds of cyanogen. 



How is it obtained ? § 7J 6. Describe its properties. In what way is 
it formed? § 717. What is paracyanogen? How is ferrocyanid of 
potassium formed? 



CYANOGEN. 379 



1 . Compounds of Cyanogen with Oxygen, 

§718. Cyanic Acid; CyO, HO; Equivalent, 43*25. — 
When cyanogen gas is passed into a solution of potash, 
a decomposition similar to that caused by chlorine (§ 519) 
takes place, producing cyanate of potassa and cyanid of potas- 
sium ; but it is difficult to separate them, and this process is 
consequently never employed. We can easily form a cyanate 
by oxydizing a cyanid. If we attempt to separate cyanic 
acid from its salts by an acid, it is instantly decomposed, its 
elements uniting with those of water to form carbonic acid 
and ammonia, C2NO, HO + 2HOr:=NH3 + 2C02. 

§ 719. It is obtained by distilling cyanuric acid, a 
compound having the composition CygOg + SHO. When 
heated, this body is resolved into three equivalents of 
cyanic acid, which passes over, and is condensed in a 
cooled receiver. It is a very volatile, pungent, acid liquid, 
and is exceedingly corrosive to the skin. It can be pre- 
served but a few minutes, and when removed from the 
cooling mixture, becomes very hot, appears singularly 
agitated, and in the course of a few minutes is wholly con- 
verted into a white insoluble matter. This singular body 
is cyamelide-, and is isomeric with cyanic acid. When 
heated, it is resolved into cyanic acid ; and the same curious 
change from cyanic acid to cyamelide, and back again to 
the acid, may be repeated indefinitely. The relation between 
these bodies is not well understood, but the difference of 
properties is probably dependent upon the different arrange- 
ment of their constituent atoms, (§ 688.) 

§ 720. Cyanates. — Cyanic acid forms a large number of 
salts with bases, having the general formula, CyO, MO. 
The acid is therefore monobasic. A few of the more im- 
portant of them will be noticed. 

Cyanate of Potash, — This salt is best formed by oxydizing 
cyanid of potassium. If we melt the cyanid and add to 
it oxide of lead, this is instantly reduced, and a pure cy- 
anate of potash is formed, KCy + 2PbO = KO CyO + 2Pb. 

§ 718. What is the action of cyanogen upon an alkaline sohi- 
tion? How is cyanic acid decomposed, when set free by an acid I ^ 719. 
How is the acid obtained? What change does it undergo ? How is this 
reaction accounted for ? § 720. How is cyanate of jwtash obtained ? 
What are its properties ? 



380 ORGANIC CHEMISTRY. 

This may be crystallized by dissolving in hot alcohol of 
80 per cent. ; on cooling, it separates in brilliant plates. 
If exposed to the air, the salt is soon decomposed, yielding 
bicarbonate of potassa and ammonia, (§ 718.) 

§ 721. Cyanate of Ammonia. — When dry ammonia and 
the vapor of cyanic acid are brought into contact, they com- 
bine to form a white salt, having the composition CyO, 
HO, 2NH3 or CyO NH4O + NH3, =: a neutral cyanate of 
oxide of ammonium, plus one equivalent of ammonia. This 
compound has all the characters of a cyanate, and yields 
ammonia with alkalies, like an ordinary ammoniacal salt. 
If we heat a watery solution of it, the second equivalent 
of ammonia is expelled, and the liquid by evaporation affords 
crystals of urea, d. new compound entirely different from 
cyanate of ammonia. 

§ 722. Urea. — This compound is derived from that pre- 
viously described, and contains CyO, NH4O, .= a neutral 
cyanate of oxide of ammonium ; but a different arrange- 
ment of its elements has taken place, and it now affords no 
evidence of the presence of either of its constituents. It may 
be C2O2 2NH2=Ur. It exists in large quantity in fresh 
urine, and may be obtained by evaporating it to a syrup, 
and mixing the residue with strong nitric acid. A sparingly 
soluble compound of nitric acid with urea separates, which 
may be decomposed by an alkali, and the liberated urea 
purified by solution in alcohol. A more elegant process is 
to decompose cyanate of potash by sulphate of oxyd of am- 
monium. The cyanate of ammonia thus formed, is converted 
into urea by the aid of heat, and may be obtained pure, by 
treating the mixture with alcohol. We have here a most 
beautiful instance of the artificial formation of an organic 
product. 

§ 723. Properties. — Urea crystallizes in square prisms like 
nitre, and has a cooling saline taste. It is very soluble both 
in water and alcohol, is an organic base, and combines with 
acids to form definite crystalline compounds. Of these, the 
nitrate is the most interesting. Its formula is UrHO, NO5. 
If we evaporate a solution of urea with nitrate of silver, the 



§ 721. What is the composition of cyanate of ammonia ? What change 
is produced by heating its solution ? § 722. How does urea differ from 
cyanate of ammonia ? Where is it found ready formed? § 723. What 
are its properties? 



CYANOGEN. 381 

elements arrange themselves so as to regenerate cyanate 
of oxyd of ammonium, and we obtain nitrate of ammonia 
and cyanate of silver, v^hich is deposited as an insoluble 
crystalline salt. 

^ 724. Fulminic Acid, Cy2 02, 2H0. — When a solution of 
nitrate of mercury or silver is mixed with alcohol and free 
nitric acid, a violent effervescence takes place, and a com- 
pound of fulminic acid with the metallic oxyd is deposited 
as a crystalline powder. The fulminic acid is the product 
of a complex reaction between the elements of the alcohol 
and acid. Ether and hyponitrous acid are first formed, and 
by their decomposition the fulminic acid is generated. 
2N03 + C4H50=:ether, give C^NsOs + SHO^CysOs, 
2HO-i-3Aq. 

This acid has never been obtained in a free state, for 
it is instantly decomposed when we attempt to liberate it. 
It is bibasic, and forms two classes of salts. Those con- 
taining two equivalents of a fixed base are neutral, as the ful- 
minate of silver, Cy202 2AgO. If these are treated with 
potash or baryta, one-half of the metallic oxyd is replaced, 
and we have a salt with two bases, as Cy202, AgO BaO ; 
but we are unable to separate all the oxyd of silver in this 
way. If we dissolve the silver salt in hot water, and add to it 
nitric acid, an acid fulminate is deposited, in which water 
replaces one atom of silver, Cy2 02, AgOHO. When the ful- 
minate of silver is digested with chlorid of ammonium, chlo- 
rid of silver is formed, and the fulminic acid with ammonia 
is instantly changed into urea, in the same m.anner as the 
cyanate. 

^ 725. All the compounds of this acid are remarkable for 
the property of exploding violently, when heated or struck, 
which makes them very dangerous, and demands the greatest 
caution in experimenting upon them. The fulminate of mer- 
cury is largely used for percussion caps, and is best pre- 
pared by the following process. One ounce of mercury 
is dissolved by a gentle heat, in one and a half ounces, 
by measure, of nitric acid, specific gravity r4, and the solu- 
tion is poured into ten measured ounces of alcohol, specific 



What change takes place when we evaporate a soUition of it with ni- 
trate of silver? § 724. What is the composition of fiUminic acid? How 
are its salts formed ? Explain the reaction. What classes of salts does 
this acid form ? § 725. What remarkable property have these salts ? 



382 ORGANIC CHEMISTRY. 

gravity -830. A violent action soon commences, and copi- 
ous white fumes are evolved After the action is jfinished, 
the fulminate is found in crystalline grains. It is carefully 
washed, and dried by a gentle heat. This salt is soluble 
in 36 parts of boiling water, and crystallizes on cooling. 

^ 726. Cyanuric Acid, CygOg, 3H0. — If to a solution of 
cyanate of potash, we add acetic acid in sufficient quantity to 
decompose two-thirds of it, we obtain a crystalline salt 
which is cyanurate of potassa and water, Cy303, 2H0 KO. 
When urea is heated, it fuses and gives off ammonia, and 
there remains behind cyanuric acid, in a peculiar state of 
combination with a portion of ammonia. In these cases the 
cyanic acid being in part deprived of its base, three equiv- 
alents of it unite to form one of cyanuric acid, it is best 
obtained by keeping urea in a state of fusion, until it is 
changed into a grayish-white substance. This is dissolved 
by heat in strong oil of vitriol, and nitric acid is added, drop 
by drop, until the solution becomes colorless. An equal bulk 
of water is then added to the solution, which on cooling de- 
posits the cyanuric acid in fine crystals. 

§ 727. This acid differs very remarkably from the two 
just described. Its permanence is seen from its mode of 
formation. It dissolves in strong nitric acid, and crystal- 
lizes from its solution unchanged. By heat it is converted 
into cyanic acid, (§ 719.) It forms large octahedral crys- 
tals, has a weak acid taste, and is sparingly soluble in cold 
water. This acid is tribasic, and forms three classes of 
salts, in which one, two, and three of its equivalents of 
water are replaced by another base. We have Cy3 03, 
3H0 ; the salt of potash, Cy303,KO 2H0, and with silver, 
^Y2^Z'> 2AgO HO, and Cy303, 3AgO. These compounds 
correspond to those of the tribasic phosphoric acids, (^ 533.) 

2. Cyanogen with Chlorine, Bromine, Sfc, 

§ 728. When chlorine acts on pure hydrocyanic acid or 
cyanid of mercury, it forms a volatile liquid, which, if kept 
for some time in sealed tubes, changes to a white crystalline 
substance. The liquid chlorid, by the action of water, is de- 
composed into hydrochloric and cyanic acids ; the last in 



What use is made of them ? § 726. How is cyanuric acid formed ? Ex- 
plain the reaction. § 727. What are its characters ? Describe its salts. 



CYANOGEN. 383 

presence of the acid, is immediately converted into chlorid 
of ammonium, with the evolution of carbonic acid. The 
solid chlorid is changed by water, into hydrochloric and 
cyanuric acids. The vapor of the solid chlorid is three 
times heavier than the other, and we may hence con- 
clude that both in this compound, and the cyanuric acid, 
three equivalents of cyanogen unite to form a compound 
atom of much greater stability than the cyanogen, CN2. 
We may therefore express the composition of the liquid 
chlorid by CyCl, and the solid by CygClg. 

^ 729. Compounds of cyanogen with bromine and iodine are 
formed, when we act upon cyanid of mercury by these bodies. 
They are white volatile solids, very poisonous, and have a 
composition analogous to the first chlorid of cyanogen. 
Cyanogen combines with nitrogen in the proportions C3N, 
to form mellone, and wilh sulphur CyS2, it produces sul- 
phocyanogen. Both of these act as compound radicals, and 
as such, will be described in their places, (§ 748 and § 752.) 

3. Cyanogen with Hydrogen. 

^ 730. Hydrocyanic Acid, Prussic ^c^c/,~CyH. — This 
remarkable compound is easily formed by decomposing 
any cyanid. with an acid. A very elegant process is to 
pass sulphureted hydrogen gas over dry cyanid of mer- 
cury. HgCy + HS=iHgS + CyH ; the acid is given off in 
a pure anhydrous state. It forms a colorless, limpid fluid, 
of the specific gravity of -697, which boils at 80°, and if 
exposed to the air, freezes by the cold of its own evapora- 
tion, forming a white fibrous mass. Its vapor is highly in- 
flammable. When pure, it is soon decomposed, and is 
changed into a brownish mass containing ammonia. It is 
one of the most fatal poisons known ; one drop is suf- 
ficient to destroy the life of a small animal. Its vapor is 
in the highest degree dangerous, and has a peculiar odor, 
resembling, when greatly diluted, that of peach-blossoms. 
This acid, when dissolved in water, is used in medicine. 

§ 731. It is easily obtained diluted with water by the fol- 

§ 728. How is the chlorid of cyanogen obtained ? What change does 
it undergo? What conclusions may we draw as to their composition ? 
§ 729. Describe the bromid, &c. § 730. What is the composition of 
hydrocyanic acid? How is it obtained from cyanid of mercury ? § 731. 
How is it obtained from ferrocyanid of potassium? What are its properties? 



384 ORGANIC CHEMISTRY. 

lowing process. Mix in a retort two parts of ferrocyanid 
of potassium, with one of sulphuric acid, and two of water, 
and distill into a receiver containing two parts of water, until 
the condensed liquid is equal to four parts. This acid, from 
a trace of sulphuric acid which it contains, is not at all liable 
to decomposition. The operation should be conducted 
under a well-drawing chimney, to avoid the vapors of the 
acid. 

^ 732. Hydrocyanic acid forms cyanids with metallic ox- 
ydsCyH + MOz=MCy-}-HO. When mixed with strong hy- 
drochloric acid, it produces with the elements of water, 
formicacid and ammonia,C2NH + 4HO=rC2H03 + NH40; 
the latter unites with the hydrochloric acid to form chlorid 
of ammonium. 

4. Cyanogen and Metals. 

§ 733. Cyanid of Potassium, KCy. — When potassium is 
heated in cyanogen gas, it takes fire and burns with a beau- 
tiful flame, forming a white compound, which is pure cyanid 
of potassium. It is best obtained by heating the ferro- 
cyanid of potassium to whiteness, in a carefully closed iron 
vessel. It has been said that this salt may be viewed as 
FeCy, 2KCy; by heat the cyanid of iron is converted into 
a carburet, and the pure cyanid of potassium may be obtained 
by boiling the powdered mass with alcohol of 60 per cent., 
which deposits it on cooling. It is a very soluble and 
fusible salt, and crystallizes in cubes. By exposure to the 
air, it attracts moisture and carbonic acid, and is slowly de- 
composed, evolving hydrocyanic acid with its characteristic 
odor. It is exceedingly poisonous, having all the medicinal 
properties of hydrocyanic acid. This salt may be compared 
to potassium in its power of reducing oxyds to the metallic 
state. The cyanids of sodium and ammonium are very 
similar. Cyanids of zinc, cobalt^ and nickel are obtained as 
insoluble precipitates by double decomposition. 

^ 734. Cyanid of Iron. — There exist two or three com- 
pounds of cyanogen and iron, which are however unknown 
except in combination, when they form an extensive series 
of compounds. 

§ 732. How does hydrocyanic acid act with oxyds ? Describe the de- 
composition by hydrochloric acid, and illustrate it upon the black-board. 
§ 733. What is produced when potassium burns in cyanogen? How is 
this salt generally formed ? What are its properties ? 



CYANOGEN. 385 

Cyanid of Mercury, HgCy. — The affinity of cyanogen and 
mercury is very powerful. Cyanid of potassium dissolves 
oxyd of mercury with great facility, forming the cyanid, 
while potash is set free, KCy+HgOrrHgCy + KO. It 
is easily obtained by saturating dilute hydrocyanic acid with 
oxyd of mercury. It crystallizes in prisms, has a disgust- 
ing metallic taste, and is very poisonous. Cyanid of silver 
is formed by the action of hydrocyanic acid or a soluble 
cyanid, upon nitrate of silver. It is a white insoluble pre- 
cipitate, resembling the chlorid. 

Cyanid of Palladium. — The affinity of this metal for cy- 
anogen is even greater than that of mercury, so that cyanid 
of mercury readily precipitates palladium from its solution, 
thus enabling us to separate it from all other metals. 

^ 735. Cyanid of Gold. — Two cyanids of gold are 
formed by treating the two chlorids with cyanid of potas- 
sium ; they are yellow powders, insoluble in acids, but solu- 
ble in cyanid of potassium, and are analogous in compo- 
sition to the two oxyds, being AuCy and AuCyg. Cyano- 
gen combines with all the other metals, forming many in- 
teresting compounds which our limits do not permit us to 
describe. 

5. Double Cyanids. 

^ 736. Many of the metallic cyanids are easily dissolved 
in cyanid of potassium, and form with it crystallizable com- 
pounds, which- contain the elements of cyanogen combined 
in a peculiar manner with potassium and the other metal. 
The metal in these compounds is not precipitated by sulphu- 
rets, chlorids, or caustic alkalies, and sometimes not even by 
strong acids. These combinations are soluble in water, but 
the salts of many of the metals decompose the solutions, 
and form insoluble double cyanids. 

^ 737. The general formula for these compounds with 
potassium is MCy, 2KCy ; the two equivalents of K may 
be replaced by two of any other metal. When hydrogen 
takes the place of the potassium, it gives rise to a new 

§ 734. Describe the cyanid of mercury, and the reaction of the oxyd 
with cyanid of potassium. What is said of the cyanid of silver ? Of pal- 
ladium ? § 735. What is the composition of the cyanids of g-old? § 736. 
What is said of the compounds of the metallic cyanids with cyanid of 
potassium ? 

33 



386 ORGANIC CHEMISTRY. 

and peculiar compound, MCy +2HCy, which has strong acid 
properties, and is capable of combining with bases, to form 
the peculiar salts of its class. These compounds have been 
regarded merely as compounds of two cyanids, and the 
acids were hence considered as combinations of hydrocyanic 
acid with a metallic cyanid, but several considerations 
present themselves against this view. We must suppose 
that the strong acid properties of these substances are due 
solely to the presence of hydrocyanic acid. This is a very 
feeble acid, and its soluble sails are all decomposed by the 
carbonic. The double acids, on the contrary, decompose 
the compounds of carbonic acid, and even dissolve the in- 
soluble carbonates. Hydrocyanic acid is a deadly poison, 
while these are harmless. It seems improbable that these 
differences are due to the combination of the hydrocyanic 
acid with a neutral, inert substance, and we are led to re- 
gard them as containing compound radicals, combined with 
hydrogen. 

IV. FERROCYANOGEN, Cj-^Fe^zCfy. 

^ 738. This hypothetical body is the assumed basis of the 
ferrocyanids. It is bibasic, and combines with two equiv- 
alents of hydrogen to form the ferrocyanic acid, which 
may be replaced by two of any metal. These compounds 
are thus represented : 

Ferrocyanic acid. CfyH 2 =Cy3Fe,H2. 

Ferrocyanid of potassium, CfyK 2 - - - - =:Cy3Fe,K2- 
Ferrocyanid of potassium and barium, Cfy, KBa=Cy3Fe,KBa. 

^ 739. Ferrocyanic Acid.-— This substance is best pre- 
pared by mixing a cold saturated solution of ferrocyanid 
of potassium, with one-fourth its volume of strong hydro- 
chloric acid, and then agitating the mixture with one-half its 
bulk of pure ether. The ether rises to the surface, with a 
white crystalline substance, which maybe washed with ether 
and dried. This is pure ferrocyanic acid. It is soluble 
in water and alcohol, has an astringent taste, and decomposes 

§ 737. What is the general composition of these? What are formed 
when hydrogen displaces the potassium? What reasons are given for 
supposing these to contain complex radicals ? § 738. What are the com- 
position and formula of ferrocyanogen ? What ia the general composi- 
tion of its compomids? §739. What is ferrocyanic acid, and what are 
its properties ? 



FERROCYANOGEN. 387 

oxyds, forming ferrocyanids. Its formation may be ex- 
plained thus : Cfy,K2 + '-^HCl=:CfyH2 + 2KCl. 

^ 740. Ferrocyanid of Potassium, Yellow Prussiate of Pot^ 
a^A, Cfy,K2, + 3HO. — The preparation of this salt has been 
before alluded to, {^ 717,) and it now remains to explain 
the theory of its formation. When a solution of cyanid of 
potassium is digested with metallic iron, the metal is dis- 
solved, and hydrogen is disengaged, 3KCy + Fe=:2KCy, 
FeCy+K. The potassium decomposes water, with the 
evolution of hydrogen, to form potash, which with ferrocyanid 
of potassium remains in solution. A similar decomposition 
takes place with oxyd or sulphuret of iron, yielding potash 
or sulphuret of potassium. 

This salt crystallizes in large and transparent honey-yel- 
low crystals, which belong to the trimetric system. It has a 
slightly saline taste, and may be swallowed in large quanti- 
ties with impunity. By a gentle heat it loses its three equiv- 
alents of water, and forms a yellowish powder. It gives 
very characteristic precipitates with many metallic salts ; 
with those of copper, a deep rich brown, which renders it 
a very delicate «test for that metal; with a protosalt of iron, 
a whitish precipitate, rapidly growing blue in the air ; and 
with a persalt of iron, a superb blue compound, which will 
be next described. 

^741. Ferrocyanid of Iron ; Prussian Blue, CfygFe^ 
or CygFe^. — This is one of the most interesting compounds 
of its class. It has long been known as a superb blue 
pigment, but until recently, its real constitution was not 
understood. Its formation may be explained by the follow- 
ingformula:2Fe2Cl3 = Fe4Cl6 and SCfyKsrrrCfygKo, yield 
Cfy3Fe4 + 6KCl. Three equivalents of ferrocyanid, con- 
taining 6 equivalents of potassium, require 6 of chlorine, which 
correspond to 4 equivalents of iron, and hence arises the ap- 
parently anomalous proportion of 3Cfy to 4Fe. The reac- 
tion is the same, if any other persalt of iron is used instead 
of the chlorid. If prussian blue is digested with pure potash, 
peroxyd of iron separates, and ferrocyanid of potassium is 
formed. It is not generally affected by acids, but if freshly 



§ 740. How is ferrocyanid of potassium prepared? Explain the reac- 
tion. Describe the salt. What are its reactions with salts of copper and 
iron? § 741. How is prussian blue obtained? Explain the reacliou on 
the black-board? 



388 ORGANIC CHEMISTRY. 

precipitated, dissolves in great quantity in oxalic acid, and 
yields a deep blue solution, which when diluted forms the 
beautiful blue ink, now so much used. Ferrocyanogen forms 
compounds with all the other metals. When the ferrocyanid 
of potassium is mixed with solutions of baryta or lime, a 
double salt is precipitated, having the composition Cfy, KBa, 
one equivalent of potassium being' replaced by barium or 
calcium. When chlorine gas is passed through a solution 
of the ferrocyanid of potassium until the liquid no longer pre- 
cipitates a persalt of iron, we obtain by evaporation and 
cooling, crystals oiferridcyanid of potassium, 

V. FERRIDCYANOGEN, CygFeg =:Cfdy. 

§ 742. This radical contains the elements of two equiva- 
lents of ferrocyanogen, and is tribasic. It is not known in 
a separate state, but forms like the last described radical, an 
acid with hydrogen, and salts with the metals. 

Ferridcyanic acid, CfdyH3. — This may be obtained in a 
separate state and resembles the ferrocyanic acid. 

§ 743. Ferridcyanid of Potassium. — -The preparation of this 
salt has been already described, (§ 741.) It crystallizes in 
beautiful prisms of a rich dark red, which are anhydrous. 
This salt may be viewed as a compound of ferrocyanogen 
CfygKg, and its formation may be explained thus : 2Cfy 
K2=.Cfy2K4 + Cl = KCl + Cfy2K3 = CfdyK3, It does not 
precipitate the persalts of iron, but, with the protosalts, it 
produces prussian blue by a complex reaction, ferrocyanid 
of potassium being formed at the same time. 

VI. COBALTOCYANOGEN, Cy6C02=Cky. 

§ 744. This is a peculiar tribasic radical, analogous to 
the last, and forms with bases a series of salts. The co- 
baltocyanid of potassium, CkyKa, is a remarkably perma- 
nent substance, and may be boiled with the strongest acids 
without being altered. Two similar series of compounds 
are known, in which manganese and chromium take the 
place of cobalt. 

How is blue ink prepared ? How does potash act upon prussian 
blue? § 742. How is ferridcyanid of potassium formed? What is its 
composition? § 743. Describe the salt. Explain, its formation on the 
black-board. What is its reaction with salts of iron? § 744. What is the 
composition of cobaitocyanogen ? 



SULPHOCYANOGEJf. 389 



VII. PLATINOCYANOGEN, Cy2Pt = Cpy. 

§ 745. This compound has not heen isolated, but forms a 
series of beautifully colored salts. The platinocyanid of 
potassium is CpyK2' ^^^ ^^^ hydrogen compound CpyH2 
is a powerful acid. Palladium and iridium form similar 
combinatioiw. 

Double Cyanids of other Metals^ 

§ 746. The insoluble cyanids of the other metals, (those 
of the earths excepted,) are also soluble in cyanid of po- 
tassium, and give by evaporation double salts, from which 
the metals are not precipitated by alkalies. They are all, 
however, decomposed by acids, which throw down the cy- 
anid unaltered. There are no compounds of these metals, 
analogous to the hydrogen acids, just described. When the 
salts of this class are submitted to electrolysis, instead of 
yielding a hydracid at one electrode, and potash at the other, 
as in the ferrocyanid of potassium ; the potassium and the 
other metal are separated at the negative pole, and cyanogen 
at the other, a decomposition precisely analogous to that 
suffered by ordinary double salts, as chlorid of platinum and 
potassium. 

^ 747. Many of these compounds are exceedingly import- 
ant in electro-metallurgy, (^ 247.) Silver and gold are 
invariably deposited in this process, from solutions of their 
double cyanids. The silver compound is generally formed 
by dissolving the oxyd of silver in a solution of cyanid of 
potassium. A cyanid of silver is formed, KCy+AgOi= 
KO+AgCy, which dissolves in an excess of the salt to 
form the compound KCy, AgCy. A cyanid of gold and po- 
tassium is obtained by a similar process. 

VIII. SULPHOCYANOGEN, CyS2— Csy. 

§ 748. Cyanogen unites with sulphur to form a new rad- 



§ 745. What is the composition of platinocyanoafen? § 746. What is 
said of the double cyanids of the other metals? How does the result of 
their electro-chemical decomposition differ from that of the ferrocyanids ? 
^747. What important application have these compounds? How are 
they generally prepared ? 

33* 



390 ORGANIC CHEMISTRY. 

ical, sulphocyanogen, which yields an acid with hydrogen, 
and salts with bases. It has not been isolated, but is form- 
ed when ferrocyanid of potassium is heated with sulphur. 
The iron is converted into sulphuret, and two equivalents of 
the cyanogen combine with sulphur to form the new radical, 
which unites with the potassium. 

§ 749. Sulphocyanic Acid, CsyH. — This acid is obtained 
by decomposing sulphocyanid of lead by sulphureted hy- 
drogen, and is a very pungent volatile fluid. It is decom- 
posed by metallic oxyds, the equivalent of hydrogen being 
replaced by a metal, to form a sulphocyanid. 

^ 750. Sulphocyanid of Potassium, CsyK. — This salt is 
readily prepared by fusing in an iron vessel at a gentle heat, 
46 parts of dry ferrocyanid of potassium, 32 of sulphur, and 
17 of pure dry carbonate of potash. The mixture is kept cov- 
ered and stirred occasionally, until the evolution of gas has 
ceased, and the vessel is heated to dull redness. The 
sulphocyanid is dissolved out by water, and crystallizes by 
evaporation and cooling. It forms long colorless prismatic 
crystals, of a sharp saline taste, which are deliquescent and 
very soluble both in water and alcohol. It is poisonous. 
With persalts of iron it produces a sulphocyanid of a 
deep biood-red, which affords a very delicate test of the 
presence of this metal. 

^ 751 . When chlorine acts on a solution of sulphocyanid of 
potassium, a yellow powder separates, which was consider- 
ed as sulphocyanogen, but is really a compound of that body 
with a little sulphocyanic acid and water. When this is 
heated, it gives off sulphuret of carbon, sulphur, water, and 
some other substances ; and a yellowish powder remains, 
having the composition C6N4. This body has been called 
mellone. 

IX. MELLONE, CeN^mMl. 

^752. The preparation of this body has just been described ; 
it bears an ordinary red-heat without change, but at high- 



§ 748. What is the composition of sulphocyanogen ? Explain the form- 
ation of a sulphocyanid. §749. How is sulphocyanic acid obtained? 
§ 750. Describe the preparation and properties of sulphocyanid of po- 
tassium. What is the reaction v^^ith persalts of iron? § 751. How does 
chlorine act upon this salt ? What change does it undergo by heat ? 
§ 752, What are the composition and properties of mellone ? 



MELLONE. 391 

er temperatures is resolved into a mixture of 3 volumes of 
cyanogen and 1 of nitrogen. It is a radical, like cyanogen, 
forming an acid with hydrogen, and salts with bases. If we 
fuse iodid or sulphocyanid of potassium, and gradually add 
to it mellone, the iodine or sulphocyanogen is expelled, and 
a mellonid of potassium is formed. 

§ 753. Hydromellonic Acid, MIH. — This is formed by 
adding hydrochloric acid to a hot solution of mellonid of po- 
tassium: the acid is deposited as a white powder on cooling. 
It is a strong, well marked acid, and decomposes acetate of 
potash, forming mellonid of potassium, and liberating the ace- 
tic acid. 

§ 754. Mellonid of Potassium^ MIK. — Its preparation has 
been described ; it is purified by crystallizing the residue, and 
washing the crystals in alcohol, which dissolves the sul- 
phocyanid, and leaves the mellonid. It forms delicate nee- 
dles containing 5 equivalents of water, and has a bitter taste. 

When sulphocyanid of ammonium is decomposed by heat, 
it yields a white insoluble substance called melam. This is 
decomposed by boiling with caustic potash, and yields two 
new substances, which are proper organic bases, combining 
with acids to form salts. They are called melamine and 
ammeline, and have the composition respectively of CgHgNg, 
and C6H5N5O2. All these substances give mellone when 
heated to redness. 

VII. CARBONIC OXYD AND CYANOGEN. 

A combination of these two bodies is supposed to exist 
in uric acid. We shall first describe the acid, and then ex- 
plain its theoretical composition. 

§755. Vric Acid,C^^'NJ{^OQ,ox C3 0N4H2O4, 2H0:= 
Ur. — 8yn, Lithic Acid* — This exists in large quantities 
in the urinary excretions of birds and reptiles, as a white 
earthy matter, which is a urate of ammonia. The urine 
of man and quadrupeds contains but small quantities of it ; 
but in disease its secretion is often augmented, and it fre- 
quently forms urinary calculi. 

How does it act on iodid of potassium? § 753. Describe hydromellonic 
acid. § 754. What are the characters of mellonid of potassium ? What 
is the result of the decomposition of sulphocyanid of ammonia? How 
are ammeline and melamine obtained, and what are their properties ? 
§ 755. In what circumstances does uric acid occur ? 



392 ORGANIC CHEMISTRY. 

It is best prepared by dissolving the urine of serpents in 
caustic potash, and decomposing the purified solution of urate 
of potash, by hydrochloric acid. It is a white crystalline 
powder, requiring 2000 parts of boiling water to dissolve it ; 
the solution has an acid reaction. It forms sparingly soluble 
salts. 

When submitted to the action of oxydizing agents, it yields 
a series of very remarkable compounds. To account for 
the changes which it undergoes, Liebig has proposed to con- 
sider it as containing a hypothetical body, which is C8N2O4, 
or 2(C2 02Cy) = 2 equivalents of cyanid of oxalyle. This 
substance, which is named cyanoxalic acid, or urylez=z\}\^ he 
supposes to be combined with 1 equivalent of urea ; CgNg 
04 4-C2N2H402 = CioN4H406. This view is supported 
by the fact, that when uric acid is oxydized, we obtain a com- 
pound derived from uryle, while urea separates. The anal- 
yses of the urates by Bensch, have shown that the acid is 
bibasic, and forms salts having the composition C10N4H2 
04,2KO. The real acid is, therefore, C-LQN4H2O4 ; 
if from this we subtract the elements of uryle, C 81^2^4 '^^^^® 
remains C2N2H4. This is equal to an ammidid of cyano- 
gen, C2N, NH2 =AdCy, which, by uniting with 2 equivalents 
of water, forms urea. Urea, therefore, cannot exist in the dry 
acid, which may be represented as Ul,AdCy. This is 
combined in the crystallized acid with 2 equivalents of 
water, which may be wholly, or in part, replaced by a base. 

From the large number of compounds derived from the 
oxydation of uric acid, we select only a few examples. 

§ 756. Allantoin C4N2H3O3. — This curious body is 
found in the allantoic fluid of the cow, but may be artificially 
formed from uric acid. It is obtained by boiling the acid 
with peroxyd of lead, when urea separates, and the uryle is 
oxydized, giving rise to allantoin and oxalic acid. It forms 
brilliant crystals, which are sparingly soluble. 

§ 757. Alloxan, C8H4N2^io- — This substance is formed 
when uric acid is oxydized by means of strong nitric acid. 
It contains the elements of uryle, plus 2 equivalents of ox- 



Describe its preparation and properties. What products are obtained 
by its decomposition? What is uryle, and with what is it combined in 
this acid? How does the ammidid of cyanogen form urea? §756. 
What is allantoin, and how obtained? § 757. How is alloxan prepared, 
and what are its properties ? 



BENZOYLE. 393 

ygen and 4 of water. It is very soluble, anci when in con- 
tact with alkalies, unites with the elements of 2 equivalents 
of water, to form alloxanic acid, which is bibasic. 

^ 758. AUoxantine, C8H5N2 0io- — In contact with de- 
oxydizing agents, alloxan combines with an equivalent of 
hydrogen and forms alloxantine. When sulphureted hydrogen 
is passed through a solution of alloxan, sulphur is set free, 
and alloxantine is deposited in white crystals, which are 
sparingly soluble in water. 

^ 759. Murexide. — This substance is best formed by mix- 
ing a boiling solution of alloxan and alloxantine, with one 
of carbonate of ammonia. The mixture assumes a dark 
purple tint, and on cooling deposits crystals of murexide. 
This beautiful substance forms square prisms, which are of a 
deep red color, by transmitted light, but have a green me- 
tallic lustre by reflected light. It is slightly soluble in cold 
water, and is decomposed by boiling water. Its composition 
is not well understood; the most probable formula is Cjg 
HgNgOg. The reaction producing it is also unexplained, 
but it requires the presence of alloxan, alloxantine, and am- 
monia. 

X. BENZOYLE, Ci4H502=Bz. 

§ 760. This radical is the basis of a large class of com- 
pounds, embracing the oil of hitter almonds and benzoic acid. 
Benzoyle, or at least an isomeric modification of it, has been 
isolated, and, will be described in connection with the pro- 
cess for its formation. This radical combines with hydro- 
gen to form the following compound. 

^761. Hydruret of Benzoyle, — Essential Oil of Bitter 
Almonds, Ci4H6 02=BzH. — To obtain this substance, bit- 
ter almonds are bruised, digested for some hours in a large 
quantity of water, and distilled, when the oil passes over, 
mixed with hydrocyanic acid and some other impurities. 
It is purified by redistillation from. a mixture of protochlorid 
of iron and quick-lime. 

It is a colorless fluid, having a pungent, burning taste, and 

How is it derived from uryle ? § 758. How is alloxantine formed from 
alloxan? Describe the reaction of alloxan with sulphureted hydrogen. 
§ 759. How is murexide prepared, and what are its charactei's ? § 7G0. 
What is the nature of benzoyle? § 761. What is the composition of the 
oil of bitter almonds ? How is it obtained ? What are its properties ? 



394 ORGANIC CHEMISTRY. 

a peculiar fragrant odor, well known as that of bitter 
almonds. It boils at 356°, but its vapor passes over with that 
of water at 212°; its specific gravity is 1*073. It is ex- 
tensively used in flavoring articles of food, but the crude oil 
which is sold for this purpose is exceedingly poisonous. 
From the experiments of Pereira, the pure oil is harmless. 
When exposed to the air, it absorbs 2 equivalents of oxygen 
and produces benzoic acid ; heated with hydrate of potash, 
it evolves hydrogen, and benzoate of potash is formed, KO, 
HO + BzH = KO, BzO + Hg. 

^ 762. Benzoic Acid, C14H5O3, HOr=:BzO, HO.— This 
acid is formed as above described, by the oxydation of 
hydruret of benzoyle ; but it occurs ready formed in ben- 
zoin, a fragrant resinous substance, obtained from the Lau- 
rus benzoin. From this it may be procured by exposure 
to a gentle heat, when the acid is volatilized, and con- 
denses as a white sublimate. It is also obtained by boiling 
the benzoin with lime, which forms a salt with the acid ; 
hydrochloric acid added to the previously concentrated so- 
lution, precipitates the pure acid in crystalline plates. Ben- 
zoic acid forms light silky crystals of a pearly whiteness, 
and has a pleasant aromatic taste, very little acid. When 
pure it is inodorous, but generally has a little volatile oil 
adhering to it, which gives it a fragrant odor, like vanilla. 
It is volatile at a gentle heat, evolving a suffocating vapor, 
which condenses unchanged. It is very slightly soluble in 
cold, but more easily in hot water. It forms a large class of 
salts, having the formula BzO, MO, most of which are of 
but little importance. 

^ 763. Chlorid of Benzoyle, Bz CI. — This is formed when 
dry chlorine gas acts upon the hydruret ; BzH and 2Cl = Bz 
Cl + CIH. It is a colorless liquid, and yields with alkalies 
a chlorid and a benzoate. Thus Bz Cl + 2K0r:r:K0, BzO 
4-KCl. When distilled with metallic bromids, iodids, cy- 
anids, and sulphurets, it yields compounds of benzoyle with 
these radicals, which resemble the chlorid in their reactions. 



What is said of its poisonous characters ? What reaction takes place 
when the oil is heated with caustic potash? Explain it on the black- 
board. §762. How is benzoic acid generally obtained? Describe the 
process with lime. What are its propi^rties? § 763. How is the chlorid 
prepared? What are the products of its reaction with potash? What 
other compounds of benzoyle are here mentioned? 



BENZOYLE. 395 

They are crystalline solids, with the exception of the cy- 
anid, which is a fragrant liquid, having the odor of cinnamon. 

^ 764. Benz amide, Ammidid of Benzoyle, is formed when 
dry ammonia acts on the chlorid, or any of the compounds 
of benzoyle just described, BzCl+ AdH^BzAd-f HCl. 
which combines with the excess of ammonia. It is solu- 
ble in hot water, and forms beautiful colorless prisms on 
cooling. Acids and alkalies decompose it inr a manner 
analogous to oxamide, (^ 705.) 

§ 765. Benzole, C^^^q- — When benzoic acid is dis- 
tilled with slaked lime, it is resolved in carbonic acid and 
benzole. It is also formed by passing the vapor of benzoic 
acid through a red-hot gun barrel ; 1 equivalent of the acid, 
Ci4H503, HO=rCi2H6 + 2C02. This substance is one 
of the numerous compounds of carbon and hydrogen, which 
organic chemistry has made known to us. It is a colorless 
liquid, with a fragrant etherial odor and a specific gravity of 
•850. It yields many new and interesting products, by the 
action of chlorine and other bodies. With sulphuric and 
nitric acid, compounds are obtained, in which an equivalent 
of hydrogen is replaced by SO2 or NO4. They are called 
sulphobenzole, C12H5SO2, and nitrohenzole, C12H5NO4. 
Dinitrohenzole, C12H42NO4, is formed by the replacement 
of 2 equivalents of hydrogen by nitrous acid. 

^ 766. Benzoine, G^^^q02' — This body is formed when 
the crude oil of bitter almonds is digested with a solution of 
potash ; it forms small white crystals, soluble in alcohol. 
It is very rem'arkable, as having apparently the same compo- 
sition as the oil of bitter almonds ; but some late results have 
made it probable that it may be C28H12O4J ^^ double the 
equivalent of that compound. When its vapor is passed 
through a red-hot tube, it is resolved into the oil of bitter al- 
monds ; fused with caustic potash, it forms benzoate of pot- 
ash. 

^ 767. Benzile. — When we act upon benzoine by chlo- 
rine or nitric acid with the aid of heat, we obtain a peculiar 
substance, which has been named benzile ; it has the same 
composition as benzoyle, CJL4H5O2, and may be considered 

§ 764. Describe the formation and properties of benzamide. § 7G5* 
How is benzole formed? What is its composition? How is nitroben- 
zole derived from it? Give its formula. § 766. How is benzoino obtained ? 
What is said of its composition? What are the reactions mentioned • 
§ 767. How is benzile obtained ? What is said of its composition I 



396 ORGANIC CHEMISTRY. 

as that radical itself. It is probably, however, an isomeric 
modification of it. 

When we act upon oil of bitter almonds by sulphuret of 
ammonium, we obtain a new substance, C14HGS2 ; it pre- 
serves the type of benzoyle, and may be viewed as this 
substance, having its oxygen replaced by sulphur. It forms 
a series of compounds, which have not yet been fully studied. 

^768. Nitrohenzoic Acid, C14H4NO7HO.— This com- 
pound is formed when benzoic acid is boiled with strong ni- 
tric acid ; it is benzoic acid in which 1 equivalent of hydro- 
gen is replaced by 1 of nitrous acid. When distilled, it is 
decomposed into nitrohenzole and carbonic acid ; a change 
analogous to that which benzoic acid undergoes, (^ 765.) 

The number of compounds formed by the transformations 
of benzoyle and its derivatives is very great. They have 
been very laboriously studied by Laurent and other chem- 
ists, whose united researches have made known, to us about 
seventy bodies derived from this radical, and future examin- 
ations may greatly increase the number. 

Substances having relations to Benzoyle, 

§ 769. Amygdaline, C4oNH27022- — This remarkable 
body is found in bitter almonds, in the kernels of the peach, 
and many other trees of the genera, prunus and amygda- 
lus. It is extracted from bitter almonds, from which the 
fatty oil has been expressed, by boiling in strong alcohol. 
When pure, it is a white crystalline substance, soluble in 
water and alcohol. 

Bitter almonds contain besides 4 or 5 per cent, of amyg- 
daline, a large quantity of albuminous matter called synap- 
tase, or emulsine. When we mix a solution of 10 parts of 
amygdaline with one of 1 part of emulsine, a curious de- 
composition ensues ; the liquid acquires the odor of hydruret 
of benzoyle and hydrocyanic acid, and when distilled yields 
the crude oil of bitter almonds. The solution contains, be- 
sides these, sugar and formic acid. This singular change 

What product is obtained by the action of sulphuret of ammonium on 
oil of bitter almonds? §768. What is nitrohenzoic acid? Explain the 
reaction it suffers by heat. (See § 765.) § 769. From what sources is 
amygdaline obtained ? What are its properties ? What other substance 
do almonds contain ? Describe the decomposition of amygdaline by 
emulsine. 



BENZOYLE. 397 

appears to be due entirely to the action of the emulsine, for 
if that is exposed to the heat of boiling water, it becomes 
insoluble and no longer acts on amygdaline. From this we 
learn that the flavor of bitter almonds arises from the reac- 
tion of their principles after they are bruised with water. 
By alcohol, we may separate them into amygdaline and 
emulsine, neither of which have the peculiar properties of 
the bitter almonds. 

§ 770. The precise reactions which occur in this remarka- 
ble metamorphosis are not exactly knov/n. It is probable 
that the emulsine has a share in the formation of some of the 
products ; but an equivalent of amygdaline contains the ele- 
ments of the following compounds, all of which are found 
in the liquid : 

1 equivalent of hydrocyanic acid, C2 N H 

2 " hydruret of benzoyle, Cgs K[j2 ^2 
i " sugar, Cg H5 O5 
2 " formic acid, C4 H2 Oq 
7 " water, Hy O 7 

1 " amygdaline, C40N H7O22 

^ 771. Hippuric Acid, CigNHgOs, HO. — This peculiar 
substance exists in large proportion in the urine of horses 
and cows. When pure it forms beautiful white crystals, 
which are sparingly soluble in water. If the urine is al- 
lowed to putrefy, the hippuric acid is completely decompos- 
ed, and benzoic acid is formed. When boiled with acids, it 
is decomposed into benzoic acid, and a peculiar substance 
called sugar of gelatine. 

Hippuric acid may be obtained in a very remarkable man- 
ner from benzoic acid ; this substance can be taken into 
the stomach in large quantity, (even half an ounce,) without 
any unpleasant effect, and in the course of a few hours the 
urine w^ill be found to contain an amount of hippuric acid, 
considerably greater than that of the acid swallowed. It 
is evidently formed from the benzoic acid, by the action of 
the vital oro^anism. 



To what is this transformation due? § 770. Give on the black-board 
the piobable reaction. § 771. How is hippnric acid obtained, and what 
are its properties? How is it obtained from benzoic acid? 

34 



398 ORGANIC CHEMISTRY. 



XI. CINNAMYLE, CigHgOs^Ci. 

^ 772. This radical is the basis of the oil of cinnamon, but 
is unknown in a separate form. 

Hydruret of Cinnamyle, CiHr^iC^gHgOa, H. — This is 
distilled from the bark of cinnamon. When pure, it is a 
heavy oily fluid slightly soluble in water, and possesses in 
the highest perfection, the delightful flavor of cinnamon. 
The balsams of Tolu and Peru yield a crystalline substance, 
called metacinnamine, which is an isomeric modification of 
the oil of cinnamon, as benzoine is of the oil of bitter almonds. 

§773. Cinnamic Acid, CigHsOsHOr^CiO, HO.— When 
oil of cinnamon is exposed to the air it absorbs oxygen and 
is converted into cinnamic acid. It is also formed with the 
evolution of hydrogen, when metacinnamine is heated with 
hydrate of potash, by a reaction like that affording benzoic 
acid, (^ 761.) It is found with benzoic acid in the balsam 
of Tolu, and closely resembles it in its properties, but is 
much less soluble in water. Hot nitric acid decomposes it, 
with the escape of nitrous fumes, and forms benzoic acid 
and oil of bitter almonds. A similar reaction is produced 
by nitric acid upon the oil of cinnamon ; when this is boiled 
with a solution of hypochlorite of lime, the conversion into 
benzoic acid is complete. 

XII. SALICYLE, Ci4H504=^Sa. 

§ 774. This radical is unknown in a separate state, but 
forms an interesting series of compounds. Like benzoyle, 
it combines with oxygen to form an acid, while like cyano- 
gen, it yields an acid with hydrogen, and combines with the 
metals. 

§ 775. Salicyd of Hydrogen. — Hydrosalicylic Acid^SsH. — 
This compound is obtained when we distill the flowers of 
meadow-sweet, Spirea ulmaria. It is also artificially formed 
by distilling at a gentle heat, 1 part of salicine, 1 of bi- 



§ 772. What is the composition of oil of cinnamon? What is meta- 
cinnamine ? § 773. Give the composition and properties of cinnamic 
acid. In what is it found? What are the products of the oxydation of 
the cinnamyle compounds? §774. Give the composition and properties 
ofsalicyle? §775. How is hydrosahcyhc acid obtained? How is it arti- 
ficially formed? 



SALICYLE. 399 

chromate of potash, and ] of sulphuric acid, with 12 of 
water. The salicyd of hydrogen is a colorless oily fluid, 
having the fragrant odor of the flowers of meadow-sweet, 
and a burning taste ; it has a specific gravity of 1-173, and 
boils at 380°. In contact with metallic oxyds, it forms sali- 
cyds, SaH + MO = SaM + HO. The hydruret of salicyle is 
in fact a hydracid analogous to hydrocyanic acid, and its 
aqueous solution reddens litmus. Like the hydruret of "ben- 
zoyle, it does not preexist in the plant, but is formed by the 
reaction of bodies which have not yet been studied. The 
salicyds of potassium and sodium are soluble, but with most 
of the other metals it forms insoluble compounds. 

^ 776. Salicylic acid, SaO, HO, is obtained when hydru- 
ret of salicyle is heated with excess of hydrate of potash ; 
hydrogen is evolved, and salicylate of potash is formed by a 
reaction precisely similar to that by which oil of bitter 
almonds produces benzoic acid, (§761.) It exists ready 
formed in the oil of wintergreen, combined with the oxyd 
of methyle, and may be obtained from it, by heating the oil 
with a solution of potash, when salicylate of potash is form- 
ed. From this salt, hydrochloric acid separates the salicy- 
lic acid. It^forms white crystals of sparing solubility, very 
like benzoic acid. 

§ 777. When rapidly heated, it is resolved into carbonic 
acid, and a new compound, hydrate of phenyle, which will 
be described in another place. Its formation is due to a re- 
action similar to that suffered by benzoic acid, (§ 765,) 
C14H5O5, HO=z2C02 + Ci2H602. 

§ 778. Hydruret of salicyle absorbs dry chlorine and 
forms chlorid of salicyle, SaCl ; this acts as an acid, and 
may be considered as anhydrous salicylic acid, in which 
chlorine replaces oxygen. Bromine and iodine act in the 
same manner, and nitric acid forms nitro salicylic acid, in 
which nitrous acid, NO4, replaces 1 equivalent of the hydro- 
gen of salicylic acid. Its formula is Ci4H4(N04)05, HO. 

The close resemblance of these compounds to those of 
benzoyle is remarkable, and it is worthy of notice that sali- 



What are its properties? How does it act with metallic oxyds? § 776. 
How is salicylic acid formed? How is it found in nature? Describe its 
properties. § 777. What change does it undergo by heat? §778. What 
is the composition of chlorid of salicyle and nitrosalicylic acid ? How are 
benzoyle and salicyle related to each other? 



400 ORGANIC CHEMISTRY. 

cyle differs from benzoyle only in containing two more equiv- 
alents of oxygen, and that benzoic and hydrosalicylic acids 
are isomeric. BzO, HOzzrCi^HsO^H, and SaHz=rCa4H5 
O4H. 

Appendix to Salicyle. 

§J79. Salicine, C42H29O22 = ^42^23^10+ 6H0.— 
This is the bitter principle which is found in the bark of the 
willows. It is obtained by boiling the bark in water, and 
digesting the decoction with oxyd of lead, which forms an 
insoluble compound with the coloring matter. The dis- 
solved lead is then thrown down by sulphuric acid and sul- 
phuret of barium, and on evaporation pure salicine crystal- 
lizes. It forms white, silky scales, which are soluble in 
water and alcohol, and have a pure, intensely bitter taste. 
Salicine is largely used in medicine, as a tonic and febri- 
fuge. 

When salicine is boiled with a dilute acid, it deposits a 
whitish resinous body, which is saliretine^ while grape sugar 
remains in solution. Its probable composition is Cg^H^^^ 
07,H0 and this +Ci2Hi40i4 = C42H29022. 

§ 780. When salicine is distilled with bichromate of 
potash and dilute sulphuric acid, we obtain salicyd of hy- 
drogen, with carbonic and formic acids, while a resinous 
substance remains in the retort. 1 equivalent of sali- 
retine, C30H14O7, HO, with 7 of oxygen, yields — 

4 equivalents of salicyd of hydrogen, C28H12O8 

2 *' of carbonic acid, 63 O4 

3 " of water, H3 O3 



The decomposition is due to the oxydizing power of the 
chromic acid, (^ 600,) which in the process becomes 
changed into the green oxyd of chromium. The formic, 
and part of the carbonic acid, are produced by the decomposi- 
tion of the grape sugar, formed from the salicine. The pro- 
cess never yields the amount of salicyd of hydrogen indi- 
cated, as a part of the saliretine is not decomposed. 

§ 779. What is salicine, and how obtained? What are its properties? 
What reaction is produced by dilute acids ? § 780. Explain the reaction 
by which the salicyd of hydrogen is formed. 



ETHYLE. 401 

^781. Phloridzine, O42H23O8, +6H0. — This substance 
is obtained from the root-bark of the apple, pear, and some 
other trees. It undergoes, with dilute acids, a change quite 
analogous to salicine, to which it is closely allied in prop- 
erties. Like it, phloridzine has been employed in med- 
icine as a febrifuge. 

^ 782. The relations between henzoyle, cinnamyle, and 
salicyle are very intimate. All of them form fragrant oils 
with hydrogen, and with one equivalent of oxygen, yield 
acids very closely resembling each other. The compounds 
of cinnamyle are rapidly conv^erted into those of benzoyle 
by oxydizing agents, and salicylic acid is formed in the de- 
composition of benzoate of copper. Salicyle differs from 
the others, in combining directly with metals, and forming 
acid compounds with hydrogen, chlorine, and bromine. 

These radicals seem allied in some respects to carbon 
and sulphur, forming neutral oily bodies or acids with hy- 
drogen, and acid compounds with oxygen. The relations 
of salicyle to the metals, have a considerable resemblance 
to those of sulphur. 

XIII. ETHYLE, C4H5=Ae. 

§ 783. This radical is not known in an isolated form, but 
exists, combined with oxygen and water, in alcohol. Ethyle 
appears in many respects to resemble a metal ; it unites with 
chlorine and sulphur, and its oxyd acts as a base to the most 
powerful acids. 

^784. Oxyd of Ethyle ; Ether; Sulphuric Ether, C^Yi^ 
0=:AeO. — This compound is obtained from alcohol, AeO, 
HO, by several processes. To form ether, we have only to 
remove one equivalent of water, which is effected when we 
distill alcohol with dry chlorid of zinc or tin. The strong 
affinity of these salts for water enables them to decompose 
the alcohol, and ether is set free. In practice it is always 
prepared by the action of sulphuric acid on alcohol. The 



§ 781. Describe phloridzine. § 782. How are these three radicals al- 
lied to each other ? How may the compounds of benzoyle and salicyle be 
derived from those of cinnamyle? How does salicyle differ from the 
others? § 783. What is the composition of ethyle? § 784. How is the 
oxyd of ethyle derived from alcohol ? 

34* 



402 



ORGANIC CHEMISTRY. 



best proportions are five parts of alcohol of 90 per cent., and 8 
of ordinary sulphuric acid. The mix- 
ture is placed in a flask, (a,) through the 
cork of which is introduced a thermom- 
eter (d) and two tubes, one of which (c) 
conveys away the vapors to a con- 
denser, and the other {b) is connected 
with a reservoir of alcohol. The mix- 
ture is heated to the boiling point 
(about 300°F) and carefully maintained 
at that temperature. Alcohol is now 
admitted through the tube b, in a 
quantity sufficient to preserve the orig- 
inal level of the liquid in the retort, 
the supply being regulated by a stop- 
cock. During the whole operation the 
liquid must be kept violently boiling, 
and the alcohol is then completely de- 
composed into ether and water, which 
distill over together, and condense in 
the receiver. With these precautions 
the process may be carried on for a 
long time, the only limit to it being, 
that the acid is slowly volatilized, 
in combination with a portion of the alcohol. The ether 
which floats on the water in the receiver is separated, and 
purified by distilling with a little caustic potash. 

§ 785. Ether is a colorless, limpid fluid, having the specific 
gravity of -725. It boils at 96°, and evaporates rapidly 
at ordinary temperatures, producing, by its evaporation, 
intense cold. Its taste and odor are pungent, penetrating, 
and peculiar. It is very combustible, and on account of its 
volatility should never be brought near a flame, as its vapor, 
when mixed with air, is very explosive. 

Ether is considerably used as a medicine : internally as 
a powerful stimulant ; and externally as a refrigerant, from 
the cold produced by its evaporation. The ether of the 
shops is never pure, but contains alcohol, and as it is only 
sparingly soluble in water, may be purified by agitation 




Describe the process by sulphuric acid. § 785. What are the proper- 
ties of ether? How is it used in medicine ? 



ETHYLE. 403 

with its volume of this fluid, which combines with the alco- 
hol, while the ether floats on the surface. 

^ 786. The oxyd of ethyle combines with acids, neutral- 
izing them, and forming compounds which are proper salts ; 
many of these are crystallizable, others are volatile liquids. 
These bodies are generally known as ethers, and the name of 
the acid is prefixed to them ; thus the nitrate of oxyd of 
ethyle is called nitric ether. Ethyle unites with chlo- 
rine, bromine, iodine, sulphur, and cyanogen, forming 
liquids, which are chlorids, &c., of ethyle. The compounds 
of ethyle are distinguished by the fact that their acid and 
base cannot be replaced at ordinary temperatures, by double 
decomposition. Thus the oxalate of oxyd of ethyle is not 
decomposed by a salt of lime, like the oxalate of oxyd of 
ammonium ; and the chlorid of ethyle does not, like the 
other soluble chlorids, precipitate nitrate of silver. From 
these peculiarities, some have contended that these bodies 
are not really compounds of oxalic acid with ether, and 
chlorine with ethyle. We find however analogous cases 
in the metallic salts ; the compounds of chromium, as the 
oxalate and chlorid, are not decomposed by salts of lime 
and silver. But the action of the ethyle compounds with 
alkalies shows very plainly their nature. In contact with 
hydrate of potash, they are slowly decomposed in the cold, 
but rapidly by heat, forming a salt of the acid with potash, 
and liberating the oxyd of ethyle, which combines with an 
equivalent of water to form alcohol. 

§ 787. Oxyd of ethyle combines with several acids, form- 
ing compounds in which two equivalents of the acid are 
combined with one of oxyd of ethyle, and one of water or an- 
other base. Thus the compound with sulphuric acid con- 
tains 2S03AeO,HO, and the water may be replaced by 
any metallic oxyd, as potash. These compounds have been 
regarded as double salts of oxyd of ethyle and the other 
base. Thus the salt of this acid with potash may be 
KO SOg + AeO SO3 ; but if this is its composition, we 
should expect to find the sulphuric acid manifesting its proper 
reactions with other bodies. We can however replace the 



How may it be freed from alcohol? § 786. What is said of the 
combinations of ether with acids ? What are they called ? What pecu- 
liarity have they? What reaction takes place with caustic potash? 
§ 787. What other compounds does ethyle form with acids? 



404 ORGANIC CHEMISTRY. 

equivalent of water in this acid, by baryta, and obtain a sol- 
uble salt. We cannot suppose that the insoluble sulphate of 
baryta combines with sulphate of ethyle to form a soluble 
salt, and it is therefore preferable to consider the acid as a 
compound of two equivalents of dry sulphuric acid, and one 
of oxyd of ethyle, acting as a single acid. The baryta salt 
will then be (2SO3 AeO)BaO. This view is extended 
to the other compounds of the same class. 

§ 788. Hydrated Oxyd of Ethyle; Alcohol, C4H602 = 
AeO, HO. — We have seen that this compound is formed by 
the decomposition of the ethyle compounds, when the 
nascent . oxyd of ethyle combines with water. It is 
abundantly formed by the fermentation of sugar, a process 
which will be afterwards explained, and from the products of 
this fermentation, it is obtained by distillation. The alcohol 
being more volatile comes over first, and by two or three 
such distillations it is obtained nearly pure, with the excep- 
tion of 10 or 15 per cent, of water, which may be separated 
by digesting it with quick-lime and again distilling, when it 
is obtained free from water, and is called absolute alcohol. 

^ 789. Pure alcohol is a colorless fluid, with a specific 
gravity of -795, and boils at 173^ F. It has a pungent and 
agreeable taste, and a fragrant odor. It is very com- 
bustible, and burns with a pale blue flame without smoke, 
which renders it very useful as a source of heat in chemical 
processes. The action of alcohol on the system, is well 
known as a powerful and dangerous stimulant. It is largely 
used in the operations of the arts, the preparation of med- 
icines, and the processes of chemistry. Its solvent powers 
are very great. The volatile oils and resins are dissolved 
by it, as well as many acids and saks, the caustic alkalies, 
and a large number of other substances. When acted upon 
by acids it is decomposed, the oxyd of ethyle unites with 
the acid, and the water is liberated. 

^790. Chlorid of Ethyle, C4H5C1 = AeCl.— When 
hydrochloric acid gas is passed into ether, chlorid of 
ethyle and water are formed ; AeO and ClH = AeCl+ HO. 
It is also formed when hydrochloric acid acts on alcohol and 

What is probably their real nature ? § 788. What is the composition of 
alcohol ? How is it obtained pure ? § 789. What are its properties ? 
To what uses is it appUed ? What is said of its solvent powers ? How- 
do acids act upon it ? 



ETHYLE. 405 

Other compounds of ethyle. It is a colorless liquid, of an 
aromatic odor, and is slightly soluble in water. It is very 
volatile, boils at 52° F., and has a specific gravity of -873. 

§ 791. Bromid of ethyle ; Hydrohromic e^Aer, AeBr, is ob- 
tained by distilling alcohol with bromine and phosphorus ; 
the water of the alcohol is decomposed, forming phosphorous 
and hydrohromic acids, and the latter reacts upon the ether 
in the same manner as hydrochloric acid. It closely resem- 
bles the chlorid. By substituting iodine for the bromine, we 
obtain an analogous compound, the iodide of ethyle. A cy- 
anid has also been formed. 

§ 792. Sulphur et of ethyle, AeS. — This compound is 
formed by mixing an alcoholic solution of sulphuret of po- 
tassium with chlorid of ethyle, KS + AeCl==:KCl+ AeS. It 
is a colorless fluid, having an odor like garlic. 

§ 793. Mercaptan, AeS + HS, or AeSsH. — When in the 
process just given, the solution of sulphuret of potassium 
is saturated with sulphureted hydrogen, we obtain a colorless 
fluid, which is very volatile, and has an odor like onions. 
It acts with metals as the hydruret of a compound radical 
which is the bisulphuret of ethyle. It displays a remarkable 
affinity for oxyd of mercury,* and forms with it a crystalline 
salt. 

§ 794. Ethyle combines with selenium and tellurium 
to form compounds allied to the sulphuret. The telluret of 
ethyie is extremely interesting^ as it illustrates the affinity 
of tellurium to sulphur and selenium. 

^ 795. Nitrate of Oxyd of Ethyle, — Nitric Ether, AeO 
NO5. — This compound is prepared by distilling equal parts 
of alcohol and strong nitric acid, to which we have added a 
few grains of nitrate of urea. The action of nitric acid on 
alcohol is violent, nitrous acid is formed, which decomposes 
the ether, forming hyponitrous ether and several other pro- 
ducts ; but if a little urea is present, this decomposition is 



§ 790. How is chlorid of ethyle formed? What are its properties? 
§ 791. How are the bromid and iodid obtained? § 792. Explain the re- 
action by which the sulphuret is formed. § 793. What is mercaptan ? 
How does it act with metallic oxyds? § 794. What is said of the selen- 
uret and telluret of ethyle ? § 795. W^hat is the composition of the ni- 
trate of ethyle? How is it obtained, and what are its properties? 



* Whence its name, from mercurium captans. 



406 ORGANIC CHEMISTRY. 

prevented, and the nitric acid and alcohol, form nitric ether 
and water. It is a colorless liquid of a pleasant sweetish 
taste, has a specific gravity of 1-112, and boils at 185° F. ; 
its vapor is very inflammable. 

§ 796. Hyponitrite ofOxyd ofEthyle — Hyponitrous Ether, 
AeONOg. — This is prepared by passing the vapors of 
hyponitrous acid, evolved by the action of nitric acid on 
starch, through cold dilute alcohol ; the ether passes over in 
vapor and is condensed. It is a pale yellow liquid of specific 
gravity -947, boils at 62° and has a fragrant odor of apples. 
This ether is formed with a variety of other substances, when 
nitric acid is distilled with alcohol ; an alcoholic solution 
of the impure product, constitutes the sweet spirit of nitre, 
used in medicine. 

^ 797. Borates of Oocyd of Ethyle — Boracic Ethers. — 
When chlorid of boron acts upon alcohol, we obtain two 
compounds of boracic acid with oxyd of ethyle. One of 
these is a limpid fluid of a burning taste ; it boils at 246°, 
and has a specific gravity of '885. Its formula is BOgSAeO. 
A solid vitreous compound is also obtained, which is (603)3 
AeO. 

Silicates of Oocyd of Ethyle, — Chlorid of silicon by its 
action on alcohol, produces two new ethers. They are vol- 
atile odorous fluids, of a hot pungent taste, and have the 
composition Si033AeO and (Si03)2AeO. 

§ 798. Oxalate of Oxyd of Ethyle — Oxalic Ether, AeO, 
C2O3. — This ether is obtained by distilling 4 parts of bin- 
oxalaie of potash, and 4 of strong alcohol, with 5 of sulphu- 
ric acid. The product is purified by carefully washing with 
water and redistillation. It is a colorless fluid, with an aro- 
matic smell ; it has a specific gravity of 1*094, and boils at 
364°. 

Benzoate of Oxyd of Ethyle — Benzoic ether, AeO, BzO, 
is prepared by distilling a mixture of 4 parts of alcohol and 
2 of benzoic acid, with 1 of hydrochloric acid. It is an 
oily fluid of a pleasant taste and odor, boils at 410°, and has 
the specific gravity of 1-054. 

§796. How is the hyponitrite formed? Describe it. What is the 
sweet spirit of nitre? § 797. How are the borates of ethyle obtained? 
Describe the silicates and their composition. § 798 Give the composi- 
tion and properties of oxalic ether. How is the benzoate obtained ? 



ETHYLE. 407 



1. Acid Compounds containing Oxyd of Ethyle- 

§799. Sulphethylic Acid — SulpJwvinic Acid, (Ae02S03,) 
HO. — We have already described the nature of this compound, 
(§ 787.) It is prepared by heating strong alcohol mixed 
with its weight of sulphuric acid, to the boiling point, and 
allowing the mixture to cool. It is then diluted with water 
and neutralized with chalk ; sulphate of lime separates, but 
the sulphethylate of lime remains in solution and is obtain- 
ed by evaporating to a small bulk and crystallizing. It forms 
beautiful colorless and transparent prisms, which have the 
composition, (AeO 2S03)CaO, + 2HO. This salt is very 
soluble and effloresces in a dry atmosphere. The sulphe- 
ethylate of potash, prepared by decomposing the lime-salt 
with carbonate of potash, is anhydrous. By substituting 
carbonate of baryta for chalk, in the above process, we ob- 
tain a sulphethylate of baryta in beautiful crystals. From 
its solution, dilute sulphuric acid precipitates all the baryta, 
and the sulphethylic acid is obtained as a liquid, which may 
be concentrated in vacuo. All its salts are soluble ; when 
heated with hydrated potash they evolve alcohol. When 
sulphethylate of potash is distilled with strong acids, oxyd 
of ethyle is evolved, which generally combines with the acid 
to form an ether. If we distill a sulphethylate with any salt 
as citrate of lime, for example, a decomposition ensues ; 1 
equivalent of the sulphuric acid in the sulphethylic acid 
combines with the lime, and the citric acid unites with the 
oxyd of ethyle to form citric ether. By this reaction seve- 
ral of the compounds of ethyle are formed. 

§ 800. The sulphethylic acid is very unstable ; when its 
solution is heated, or even evaporated in a vacuum beyond 
a certain point, it is decomposed into alcohol and sulphuric 
acid. The student is now prepared to understand the part 
which this acid takes, in the preparation of oxyd of ethyle, 
(§ 784 ) When we heat a mixture of alcohol and sulphuric 
acid containing 2 equivalents of acid, 1 of anhydrous alco- 
hol, and 1 of water, to about 285°, the oxyd of ethyle re- 
places an equivalent of water in the sulphuric acid, and 

§ 799. How is the siilphethyle acid prepared? Describe the prepara- 
tionjind properties of the sulphethylate of lime. What is the reaction 
when sulphates are distilled with acids? 



408 ORGANIC CHEMISTRY. 

sulphethylic acid is formed, 2(S03HO) + AeO, H0=2S03 
Ae02,HO + 2HO. At a temperature but a very few de- 
grees above this, (290° or 300°,) this acid is decomposed, 
provided the liquid is kept in steady ebullition. In this de- 
composition, it takes up an equivalent of water, and is re- 
solved into sulphuric acid and oxyd of ethyle, 2S03x^eOj 
HO,+HO=2(S03HO) + AeO. The ether when libera- 
ted at this temperature, has no disposition to combine with 
water, and form alcohol, (as at low^r temperatures,) but 
passes off in a free state. Sulphuric acid so far diluted as 
this in the mixture, readily gives off water at 285°', and 
consequently the ether evolved is mixed with aqueous 
vap6r. The whole reaction is thus readily explained by the 
fact that sulphethylic acid is formed at 285°, and decom- 
posed at a temperature a very few degrees above it, when 
the liquid is boiling. In the ether process described, 
(^ 784,) the alcohol, as it drops into the boiling mixture, 
slightly cools the liquid at the point of contact, so that sulphe- 
thylic acid is formed, and the equivalent of water eliminated 
is immediately vaporized. As soon as the newly formed 
acid is mixed with the boiling liquid,at is decomposed, and 
ether is evolved. The result of this is, that an equivalent of 
water is volatilized with each equivalent of ether, so that in 
effect, the alcohol is only resolved into these two substances. 
§ 801. Phosphethylic Acid. — This acid is formed by a pro- 
cess similar to that which affords the sulphethylic, and re- 
sembles it in its general properties. The formula of the 
phosphethylate of baryta is P05AeO,2BaO. Arsenic acid 
also forms a similar compound ; the phosphethylic and ar- 
senethylic acids have been isolated. 

2. Some products of the Decomposition of the Compounds 
of Ethyle. 

§ 802. When sulphethylic acid is so concentrated that 
it does not boil below 320°, it no longer yields ether by dis- 
tillation, but olefiant gas and water. This is, in effect, the 



How is it decomposed by heat? Explain the formation of the sul- 
phethylic acid. Under what circumstances is it again decomposed, and 
what are the products ? Whence arises the water which accompanies the 
ether? Explain the reaction in the ether process. § 801. What is the 
composition of phosphethylic acid ? • 



ACETFLE. 



409 



process before given for obtaining this gas, (§ 455,) but a 
more elegant way of preparing it, is 
by an arrangement similar to that 
used for producing ether. Sulphu- 
ric acid is diluted with nearly one 
half its weight of water, so that its 
boiling point is between 320° and 
330°, and being heated in the flask 
a to ebullition, the vapor of boil- 
ing alcohol is introduced from the 
flask d by the tube 6, which dips 
a little way in the acid. Sulplio- 
vinic acid is formed, but at this 
temperature is instantly decompos- 
ed into olefiantg-asand water, which 
are evolved ; oxyd of ethyle, C4H5 
0=:C4H4 + HO. In this way we obtain the gas pure ; no 
blackening of the acid takes place, and the process may be 
continued for any length of time. 

§ 803. When 2j parts of sulphuric acid and 1 of alcohol 
are distilled, the chief product is an oily liquid called light 
oil of wine. This, by cold, is separated into a solid white 
matter called ,etherine^ and a light oily liquid, ether ol ; both 
of these are carburets of hydrogen, isomeric with olefiant 
gas. When alcohol and ether are submitted to oxydizing 
agents, the first action is to decompose the ethyle, and give 
rise to a series of compounds which may be considered as 
containinga new radical, acetyle. 




XIV. ACETYLE, 04113= Ac. 

§ 804. Hydrated Oxyd of Acetyle^ Aldehyde, C4H4O2 = 
AcO, HO.— This compound is formed when alcohol is 
oxydized by nitric acid or other agents, but is best prepared 
by the following process. Equal weights of powdered bichro- 
mate of potash and strong alcohol are introduced into a re- 
tort, and 1^ parts of sulphuric acid very gradually added 
through the tubulure ; a gentle heat is then applied, when 



§ 802. What are the results of the distillation of concentrated siilph- 
ethylic acid ? Explain the arrangement for olefiant gas, and the theory 
of its formation. §803. What is the light oil of wine? What is the 
result of oxydation on alcohol? § 804. What is the composition of ace- 
tyle ? How is aldehyde prepared ? 

35 



410 ORGANIC CHEMISTRY. 

a mixture of aldehyde and water distills over, and is con- 
densed in a cold receiver. The reaction consists in the ab- 
straction of 2 equivalents of hydrogen, from the alcohol,* by 
the oxygen of the chromic acid ; alcohol, C4H5 0,H0, mi- 
nus 2 equivs. of hydrogen, rr:C4H30,HO, or aldehyde. 
When pure it is a colorless liquid, with a suffocating ethereal 
odor; its specific gravity is '79, and it boils at 70° F. Pot- 
ash decomposes it, forming a brown resinous matter which 
15 termed aldehyde resin. 

§- 805. When aldehyde is kept some days, even in sealed 
tubes, it is changed into two new isomeric compounds. 
One of these, elaldehyde, is a dense oily fluid which has the 
formula, C^^Yi^^^e—^ equivalents of aldehyde. The 
other, metaldehyde, crystallizes in hard white prisms, which 
do not fuse below 250°. Aldehyde unites with ammonia to 
form a neutral crystalline compound, which is called alde- 
hydite of ammonia. Its composition is C4H3 0,NH4 0, in 
which the oxyd of acetyle appears to act the part of an acid. 
When distilled with a strong acid, it, affords pure aldehyde. 
If a solution of this compound is added to a dilute solution of 
nitrate of silver, and the mixture heated, the silver is re- 
duced, and lines the vessel in which the process is per- 
formed, with a brilliant film of the metal, forming a perfect 
mirror. If we add the aldehyde to a mixture of water and 
oxyd of silver, and warm it gently, a part of the silver is re- 
duced, forming a brilliant coating on the glass, and the other 
portion is dissolved, forming a salt with an acid, which con- 

f tains the elements of aldehyde +1 equiva- 
lent of oxygen. 
^ 806. Aldehydic Acid ,—Acetylous Acid, 
AcOgjHO. — This is the acid which is form- 
ed by the action of aldehyde on oxyd of sil- 
ver. When its baryta salt is heated with 
oxyd of silver, the metal is reduced and the 
aldehydic acid combines with 1 equivalent 
of oxygen to form acetic acid. Aldehydic 
acid is formed during the slow combustion 
of ether, (^ 396,) by means of ignited pla- 

Give its composition and properties. ^ 805, What are its isomeric 
modifications? What curious property of aldehyde is mentioned? De- 
scribe the compound of aldehyde and ammonia- §806. What is the 
composition of aldehydic acid, and how is it formed ? 

* Whence its name, from alcohol dehydiogenatus. 



ACETYLE. 411 

tinum, as in the annexed figure, and has hence been<;alled 
lumpic acid. 

^ 807. Acetic Acid^ Vinegar^ Acetylic Acid, Pyroligneous 
Acid, C4H3O3, HO^iAcOg, HO. — This acid is formed by 
the slow oxydation of alcohol. Pure alcohol undergoes no 
change when exposed to the air, but if its vapor, mixed with 
air, is brought in contact v/ith platinum black, the alcohol 
slowly unites with oxygen and forms aldehyde, which read- 
ily absorbs more oxygen from the air,, and generates acetic 
acid. This may be beautifully shown by placing a little 
platinum black in a watch-glass, by the side of a small ves- 
sel of alcohol, covering the whole with a bell-glass, and set- 
ting it in the sun-light. In a short time the vapor of acetic 
acid will condense on the sides of the glass, and run down 
in drops, and if we occasionally admit fresh air by raising 
the bell-jar, the whole of the alcohol will be acidified in a 
few hours. 

§ 808. In the large way, alcoholic liquors, as wine, cider, 
and beer, are exposed to the air in open vessels ; the al- 
cohol slowly absorbs oxygen and forms aldehyde, which is 
then converted into acetic acid. This is the process for ordi- 
nary vinegar. Pure alcohol diluted with water, is inca- 
pable of undergoing this change, but the addition of a very 
small quantity of any ferment, as vinegar already formed, or 
the substance commonly called mother of vinegar, enables 
it to combine with oxygen. The action of these substances 
has been explained in a previous part of the 
treatise, (§ 690:) In this process, the es- 
sential thing is a free access of air. In the 
manufacture of vinegar on the large scale, 
this is secured by causing the liquor (h) to 
trickle from threads of cotton drawn through 
holes, over shavings of beech-wood previ- 
ously soaked in vinegar, and contained in a 
large cask with holes in its sides, {cccc,) 
so as to admit a free circulation of air. In this way a vast 
surface is exposed, and the absorption of oxygen is very 
rapid, causing an elevation of 20° or 30° in the temperature. 



§ 807. What is the composition of acetic acid ? Describe its forma- 
tion by platinum black. § 808. Describe the process for obtaining vine- 
gar from alcoholic liquors. What is formed previous to the ai^ctic acid ? 
Describe the quick vinegar procesfj. 




412 ORGANIC CHEMISTRY. 

The liquid is passed through this apparatus four or five 
times in the course of twenty-four hours, in which lime the 
change of the alcohol into vinegar is generally complete. 
The product is collected in the vessel a, 

§ 809. Acetic acid is obtained for many purposes, by dis- 
tilling wood in close vessels ; the volatile ingredients are 
expelled and charcoal alone remains ; the products are, be- 
sides carbonic acid and carbureted hydrogen, a large quantity 
of acetic acid, mixed with oily and tarry matters, from which 
it is separated mechanically. The product is called pyro- 
ligneous acid, and is largely used in the arts of dyeing and 
calico printing, but being contaminated by empyreumatic 
oils, is not fit for the purposes of domestic economy. By 
combining it with bases, we can obtain salts which, when 
decomposed, afford us a pure acid. 

^810. The concentrated acetic acid is obtained by distilling 
dry acetate of soda with strong sulphuric acid. The pro- 
duct deposits crystals by cold, which may be separated from 
the liquid, and are pure acetic acid with 1 equivalent of 
water, AcOg, HO. This equivalent of water is essential to 
the existence of the acid, and is expelled only by combining 
it with a base. The pure acid is solid at temperatures below 
60° ; when liquid its specific gravity is 1*063, and its boiling 
point is 248°. It is readily soluble in w^ater, alcohol, and 
ether. It has a pungent, fragrant odor, and is strongly acid ; 
when applied to the skin it is powerfully corrosive. The 
salts of this acid are all soluble, and when neutral, contain 1 
equivalent of base. 

1. Compounds of Acetic Acid, {Acetates.) 

§ 811. Acetate of potash, KO, AcOg, is easily prepared 
by saturating carbonate of potash with acetic acid. It is a 
very soluble, deliquescent salt, and is employed in medicine. 
Acetate of soda, NaO, Ac03-j-6Aq, is prepared in large 
quantities from pyroligneous acid. The salt is heated to 
decompose the oily matters, and is then used to afford a pure 
acid. Acetate of oxyd of ammonium is used as a medicine, 
under the name of spirit of Mindereus. It is prepared by 



§ 809. What is pyroligneous acid, and how is it obtained? What are 
its uses ? § 810. Describe the preparation and properties of the pure acid. 
§ 811. Describe the acetates of potash and soda. 



1 



ACETYLE. 413 

saturating acetic acid with ammonia, and is exceedingly 
soluble and volatile. Acetate of alumina, AI2O3, SAcOg, 
is a salt much used in dyeing. It is prepared for this 
purpose by mixing a solution of alum with acetate of lead, 
when sulphate of lead precipitates : as thus prepared, how- 
ever, it contains potash. Acetate of manganese, MnO, AcOg, 
is a fine rose-colored salt. Acetate of zinc is a beautiful 
white salt, and is used in medicine, as a tonic and astringent. 
The acetates of the two oxyds of iron are largely used ia 
dyeing, and like the salt of alumina, are prepared by double 
decomposition. 

§ 812. Acetates of Lead. — There are four acetates of lead, 
only two of which are important. The neutral acetate or 
sugar of lead, PbOjAcOg + SAq, is prepared by dissolv- 
ing litharge in acetic acid. It is a white salt, with a very 
sweet and astringent taste, and is often employed in medi- 
cine, but is poisonous, and should be used internally with cau- 
tion. When a solution of this salt is digested with oxyd of 
lead, in the proportion of six parts of the acetate to seven of 
litharge, the latter is dissolved and forms a trihasic acetate^ 
3PbO,Ac03. It is also slowly formed when metallic lead is 
digested in an open vessel with a solution of the neutral ace- 
tate, oxygen being absorbed from the air. This salt is more 
soluble than the preceding one, and crystallizes in long 
needles ; its solution has an alkaline reaction, and is well 
known in pharmacy as Goulard's extract or solution of lead. 
When exposed to the air, it absorbs carbonic acid, and 
eventually two of its equivalents of oxyd of lead are pre- 
cipitated as carbonate. This reaction enables us to explaia 
the formation of white lead, (^ 613.) 

§ 813. A process frequently employed is to mix litharge 
and about ji^^th of sugar of lead into a thin paste with water ; 
the mixture is gently heated, and a current of carbonic acid 
is passed through it. The acetate of lead dissolves a por- 
tion of the oxyd to form the tribasic salt ; this is imme- 
diately decomposed by the carbonic acid, which precipi- 
tates carbonate of lead, and leaves the acetate free to dis- 

How is acetate of alumina prepared, and for what used ? § 812. Give 
the composition of sugar of lead. Its preparation and properties. In 
what two ways is the tribasic salt formed? Describe its properties. Give 
its common name. How is it decomposed by the carbonic acid of the 
air? § 813. Describe the first process for sugar of lead. Explain the 
reaction. 

35* 



414 ORGANIC CHEMISTRY. 

solve a new portion of oxyd. In this way tbe smallest 
quantity of the acetate is able to convert a large portion of the 
oxyd into carbonate, and at the end of the process to remain 
unaltered. 

^ 814. In the ordinary process, the plates of lead are ex- 
posed to the action of acetic acid, moisture, air, and carbonic 
acid from the fermenting tan. The lead immediately be- 
comes covered with a film of oxyd by the action of the air. 
This is dissolved by the vapor of acetic acid, and forms a 
solution of neutral acetate, which moistens the plates and 
gradually acts upon them, forming by the aid of the atmos- 
pheric oxygen, the basic acetate. This is immediately de- 
composed by the carbonic acid, in the same manner as in 
the last process, and the neutral acetate is again set free to 
act upon the metallic lead ; the process goes on until all the 
lead is carbonated. In this way a small quantity of acetic 
acid will, under favorable circumstances, convert a hundred 
times its weight of lead into carbonate in a few weeks. 

^815. Acetates of Copper. — The neutral acetate forms 
beautiful green crystals, which belong to the monoclinate 
system, and contain an equivalent of water, being CuO, AcOg 
4-Aq. Copper also forms several acetates with excess of 
base, which are insoluble. The verdigris, so much used as 
a paint, is a mixture of these. All these salts are very 
poisonous. The acetate of silver is a white crystalline salt, 
and is the least soluble of the acetates. 

§ 816. Acetate of oxyd of ethyle ; acetic ether, AeO, AcOg, 
is obtained by distilling five parts of acetate of soda, eight 
of sulphuric acid, and three of alcohol. Ether and acetic 
acid are formed, and combine directly to form the compound, 
which distills over. It is a colorless, very fragrant liquid, 
andboilsat 165°. Theodorof the vinegar formed from ferment- 
ed liquors, is due to the presence of a little acetic ether. 

2. Other Compounds of Acetyle, 

^ 817. Olefiant Gas, — This body has been already de- 
scribed, (^ 455 and §802 ,) but it is again mentioned in this 

§814. Describe the common method, (§ 6 J 3.) Explain the mode of 
formation. § 815. Describe the neutral acetate of copper. What is ver- 
digris? Describe the acetate of silver. §816. Give the composition 
and properties of acetic ether. § 817. What is the reaction of chlorine 
on olefiant gas ? 



ACETYLS, 415 

place because it is probably a hydruret of acetyle^ C^Yiji^^z 
AcH. When mixed with chlorine, it forms a peculiar liquid, 
known as the Oil of the Dutch Chemists^ or Dutch Liquid, 
which contains C4H4CI2 =AcCl, HCl. This is a heavy 
oily substance, of a sweet pungent taste. When treated with an 
alcoholic solution of potash, it loses the equivalent of hydro- 
chloric acid, and chlorid of acetyle, AcGl, is evolved, which 
is a gas at ordinary temperatures. A peculiar compound 
formed by the action of chlorine on chlorid of ethyle, is 
ACCI3. 

The Action of Chlorine on the Ethyle Compounds. 

^ 818. Chlorine, aided by the sun's light, produces with 
the ethers, a very interesting class of bodies. The type is 
sometimes retained, and we have ethyle in which chlorine re- 
places the hydrogen. Thus we form C4CI5, which acts in 
combination as ordinary ethyle. More frequently the type 
is destroyed, and we obtain bodies which are referable to the 
acetyle series. When chlorid of ethyle is acted upon by 
chlorine, a series of compounds is formed, which very beau- 
tifully illustrates the law of substitution. Commencing with 
the chlorid, we obtain the following substances, by successive 
substitutions of chlorine for hydrogen : 

C4 H5 CI C4 H2 CI4 

C4 H4 CI2 C4 H C!5 

C4 H3 CI3 C4 Cl6 

When dry chlorine acts upon oxyd of ethyle, there is 
formed, besides several of the products of the last reactions, 
a new series of compounds, in which the hydrogen of the 
ethyle is gradually replaced by chlorine, the oxygen remain- 
ing unchanged. One of the products of this reaction is a 
white crystalline body, C4CI5O, which by the further action 
of chlorine, becomes chlorid of carbon, C4CI5CI, or C4Clg. 
This, as we have seen, is the ultimate result of the action of 
chlorine on the chlorid of ethyle and olefiant gas. 

§ 819. Chlorids of Carbon. — The per chlorid, C4CI6, 
which is the result of the action above described, is a white 



Describe the chlorid of acetyle. § 818. What is the action of chlorine 
on the ethers? Illustrate on the black-board, the substitution of hydro- 
gen in chlorid of ethyle. What are the products of the action of chlorine 
on ether ? § 819. Describe the perchlorid of carbon. 



416 ORGANIC CHEMISTRY* 

crystalline solid of an aromatic odor, like camphor; it 
melts at 320°, and at a temperature a little above this, may be 
distilled unaltered. It is scarcely combustible, and is un- 
changed by acids or alkalies. When its vapor is passed 
through a porcelain tube heated to redness, it is resolved in- 
to chlorine gas and a new compound, the protochlorid of car- 
bon, C4CI4, which is a volatile liquid of the specific gravity 
of 1*55. If the vapor of this compound is passed repeat- 
edly through a tube at a bright red heat, it is decomposed 
into chlorine and a dichlorid of carbon, C4CI2. This body 
forms soft, silky crystals, which are volatile and combustible. 

^ 820. Acetone, C3H3O. — This is a product of the de- 
composition of acetic acid, or of acetates, by heat. It is best 
prepared by distilling acetate of lead with quicklime, when 
acetone passes over, and is condensed in a cool receiver. 
The reaction is easily explained. Anhydrous acetic acid 
contains the elements of 1 equivalent of acetone and one of 
carbonic acid, C4H3O3 = 031130 + CO^. The carbonic 
acid combines with the lime. 

Acetone, when pure, is a limpid fluid which has a specific 
gravity of '793 and boils at 100° ; its odor is pungent and 
peculiar. It mixes in all proportions with water, alcohol, 
and etber. 

Dr. Kane supposes that the above formula for acetone 
should be doubled, and regards it as the hydrated oxyd of a 
compound radical, which he cd\\s mesityle, OgH^. Acetone 
is then OgH^O, HO. This radical he supposes to form the 
basis of a series of compounds like those of ethyle, and he 
has succeeded in obtaining the oxyd, chlorid, and iodid of 
mesityle, and a combination with sulphuric acid resem- 
bling sulphovinic acid. When an acetate is heated with 
excess of caustic potash, it is resolved into marsh gas and 
carbonic acid, as already described, (§ 453.) 

XV. KAKODYLE, C^H^As^^Kd. 

^ 821. When a mixture of arsenious acid and acetate of 
potash is heated to redness, a peculiar volatile, poisonous 
liquid is formed, which was formerly called the fuming liquor 

Describe the preparation of the other chlorids. Their composition and 
properties. §820. How is acetone obtained ? What are its properties? 
What is Kane's view of it ? § 821. What is the composition of kako- 
dyle ? From what is it named ? 



KAKODYLE. 417 

of Cadet. The late researches of Bunsen have shown that 
it is the oxyd of a peculiar complex radical, which he has 
named kakodyle* This radical he has obtained in a separate 
form. It combines with oxygen to produce an oxyd and an 
acid, forms compounds with chlorine, bromine, iodine, sul- 
phur, selenium, and cyanogen, and in all its combinations 
simulates completely the characters of a metal. 

^ 822. Kakodyle is obtained by digesting zinc with chlorid 
of kakodyle at 212°, when chlorid of zinc is formed and 
kakodyle is set free, KdCl+Zn=rZnCl4-Kd. It is purified 
by distillation in an apparatus filled with carbonic gas, and 
is a colorless liquid, which when exposed to cold, forms 
beautiful transparent prisms. It has a most disgusting odor, 
resembling that of arseniureted hydrogen, and is exceed- 
ingly poisonous. When exposed to the air it instantly takes 
fire. It burns spontaneously in chlorine gas. 

§ 823. P rot oxyd of Kakodyle, or Alkarsine, C4HgAs,0 — 
KdO. — This is obtained by heating to low redness in a glass 
retort, a mixture of equal parts of acetate of potash and arseni- 
ous acid. The oxyd of kakodyle is condensed in a receiver 
cooled by ice. When purified, it forms a liquid of specific 
gravity 1*462 which boils at 400°, and by intense cold, crys- 
tallizes in silky scales. It has a most disgusting odor, and 
its vapor when respired, even in small quantities, is fearfully 
poisonous. When exposed to the air, it emits dense white 
fumes, and soon takes fire, burning with a pale flame and 
evolving carbonic acid and water, with copious clouds of 
arsenious acid.' For this reason, all operations on the oxyd 
of kakodyle must be performed in vessels filled with car- 
bonic acid gas. The formation of this body from acetic and 
arsenious acids may be thus explained : 2 equivalents of dry 
acetic acid and 1 of arsenious acid yield 4 equivalents of 
carbonic acid and one of oxyd of kakodyle, 2 (0411303) + 
As03=::4C02 + 04HgAs, O. 

^ 824. Kakodylic Acid; Alkargene, K60^. — This is 
formed by the oxydation of oxyd of kakodyle at a low temper- 
ature, which is effected by covering it with a layer of water 

What is its character? §822. Describe its preparation and properties. 
§ 823. Describe the preparation and properties of the protoxyd. Explain 
its formation. § 824. How is kakodylic acid prepared ? 

* From the Greek, kakos, evil, and hule, principle, or matter, in allusion 
to its poisonous and offensive properties. 



418 ORGANIC CHEMISTRY. 

when oxygen is gradually absorbed from the air. It forms 
oblique rhombic prisms, very soluble in water and alcohol, 
and is a feeble acid ; unlike the other kakodyle compounds, 
it is inodorous and not at all poisonous. 

^ 825. CJdorid of kakodyle, KdCl, is obtained when hy- 
drochloric acid acts on theoxyd; KdO + HCl=:KdCl + HO. 
It is a colorless volatile liquid, and its vapor is more horribly 
disgusting than that of the oxyd. It combines with the oxyd 
to form a crystalline oxychlorid, KdO, 3KdCl. Kakodyle 
forms with bromine, iodine, and fluorine, compounds very 
analogous to the chlorid. The sulphuret is a colorless 
liquid, of a very fetid odor. It dissolves sulphur to form 
KdSg, which is a sulphur acid, and unites with metal- 
lic sulphurets to form beautiful double salts. 

The Cyanid of kakodyle, KdCy, is formed like the chlo- 
rid, and crystallizes in beautiful prisms ; it is very fusible 
and fearfully poisonous. 

APPENDIX TO ETHTLE AND ACETYLE. 

1 . Sugars, and the Products of their Decomposition. 

§ 826. The name of sugar is applied to several bodies 
which are allied in their properties. They are all capable 
of undergoing the vinous fermentation, or of yielding, by a 
peculiar decomposition, alcohol and carbonic acid. All of 
them are soluble in water, have a sweet taste, and contain 
oxygen and hydrogen in the proportions to form water. 

<^827. Ca7ze5?/^ar, Ci2HiiOiir=:Ci2H909 2HO.— This 
substance is found in the juices of many plants, as the sugar- 
cane, maple and beet root, which furnish it in large quanti- 
ties. It is obtained from these juices, by evaporating them 
to a small bulk, when the sugar crystallizes in grains. 
By the slow evaporation of a concentrated solution, it is ob- 
tained in fine transparent crystals, which are derived from an 
oblique rhombic prism ; in this state it constitutes rock 
candy. It fuses at 356°, and forms on cooling a vitreous 
mass, well known as barley sugar ; this gradually becomes 

What are its properties? How is it distinguished from the other kako- 
dyle compounds? § 825. Describe the chlorid. What other compounds 
of it are known? § 826. What are the characteristics of the sugars? 
§ 827. Give the composition and properties of cane sugar. How \a it ob- 
tained ? What is the form of its crystal ? 



SUGARS, 419 

Opaque, and changes into a mass of small crystals of ordinary 
sugar. Sugar is soluble in about one-third its weight of 
cold water, forming a thick syrup. It is but slightly soluble 
in pure alcohol. When boiled with dilute sulphuric acid, it 
gradually changes into grape sugar. Sugar forms definite 
crystalline compounds with lime and baryta, having the 
formula CjgHgOg, BaO,HO, and with oxyd of lead, C12 
H909,2PbO. 

^828. Grape Sugar, Glucose, Starch Sugar, Diabetic 
Sugar, CJ2H24O14. — This sugar is found in the juice of 
many fruits, and in honey. It is produced by the action of 
sulphuric acid on cane sugar, and by the decomposition of 
salicine and phloridzine in dilute acids, (^ 780.) It is best 
prepared by boiling starch with a dilute acid. One part of 
starch with four parts of water, and from -^-^ to -^-^ of its 
weight of sulphuric acid, are boiled for thirty-six or forty 
hours. A small quantity of oxalic acid, (about ^ioO ^^^7 ^® 
used in place of the sulphuric, with the same efl'ect. The 
solution is then mixed with chalk to separate the acid, and 
the liquid affords by evaporation pure grape sugar. As thus 
formed it constitutes an article of commerce, and is largely 
used to adulterate cane sugar. 

^ 829. In this remarkable transformation, the starch 
CjjHjoOio' combines with the elements of 4 equiva- 
lents of water, and forms C12H14O14. It is not easy to 
explain this curious reaction, as the acid remains quite 
unchanged. Several other instances of the artificial pro- 
duction of this body, will be given in another place. The 
urine in the disease called diabetes mellitus, contains a 
large quantity of grape sugar ; this is probably derived 
from the starch contained in the food, which is con- 
verted into sugar in the stomach. Grape sugar is gen- 
erally obtained as a white granular mass ; it is less 
sweet to the taste than cane sugar, and requires one and 
a half parts of cold water to dissolve it. It is more sol- 
uble in alcohol than cane sugar, and may be obtained in 
transparent cubical crystals from its alcoholic solution. 
When heated to 212° it loses 2 equivalents of \vater. 



How do dilute acids aifectit? §828. What other names are given 
to grape sugar? What is the natural source of it? How is it obtained 
from starch ? § 829. Explain the reaction. What is the origin of the 
sugar iu diabetes mellitus? What are the properties of the grape sugar? 



420 ORGANIC CHEMISTRY. 

Cane sugar when mixed with oil of vitriol is immediately 
decomposed, but grape sugar unites with it, to form a new 
acid, the sulplio saccharic. The alkalies, and lime or ba- 
ryta, readily decompose grape sugar, producing formic acid, 
and two other compounds but little known, called the glucic 
and melassic acids. Cane sugar is slowly changed into 
grape sugar when boiled with alkalies, and then affords the 
same products. 

§ 830. Saccharic Acid, C12H8O14, 2H0. — ^When strong 
nitric acid acts upon cane or grape sugar, oxalic acid is 
formed ; but if we use a very dilute acid we obtain the pres- 
ent compound. It is easily soluble, and forms a series of 
salts whose constitution is not well understood. The sac- 
charate of silver, when gently heated under water, is reduced 
and lines the vessel with a mirror-like coating of metallic 
silver. 

§831. Sugar of Milk; Lactine, C24Hj^90] 9, 5H0=r 
^24^24034. — This is found only in the whey of milk, and 
is obtained by evaporating it, and purifying the product by 
repeated crystallization. Pure lactine forms semi-transpa- 
rent prisms, which are soluble in six parts of cold and two 
and a half of hot water ; the solution has a very sweet taste. 
It is insoluble in alcohol and is changed by dilute mineral 
acids into grape sugar, by combining with the elements of 2 
equivalents of water. 

§ 832. Mucic Acid, C^^^qOj^, 2H0.— This is a product 
of the action of strong nitric acid on sugar of milk, oxalic 
acid being formed at the same time. It is a white crystal- 
line powder, of a weak acid taste, and is sparingly soluble 
in cold water. It is a bibasic acid. The ?nucic ether, mu- 
cate of oxyd of ethyle, 2AeO, C12H8O14, forms colorless 
prismatic crystals. This acid is isomeric with the saccharic 
acid. 

§833. Mannite, CgHyOg. — This substance is not prop- 
erly a sugar, as it is incapable of undergoing the vinous fer- 
mentation. It exists in the juices of many plants, and is ob- 
tained from the manna of the shops, which is the concreted 

111 what respects is it different from common sugar? 6 830. How is 
saccharic acid obtained? What are its properties? § 831. What is 
the source of sugar of milk, and how is it obtained? What are its prop- 
erties and composition? How is it affected by acids? §832. How is 
mucic acid formed, and what are its properties? § 833. From what 
source is mannite obtained ? What are its properties and composition ? 



VINOUS FERMENTATION. 421 

juice of a species of ash. This substance is dissolved in 
hot alcohol, and the mannite is deposited on cooling. It forms 
delicate silky crystals, which are slightly sweet and very sol- 
uble in water. 

2. The Vinous Fermentation, 

^ 834. It has already been mentioned that the juices of 
the grape and other fruits, when exposed to the air at ordi- 
nary temperatures, undergo a peculiar change, by which al- 
cohol and carbonic acid are produced. These products re- 
sult only from the decomposition of sugar, and hence the 
fact that any liquid is capable of producing alcohol by fer- 
mentation, is a proof that it contains sugar. A solution of 
pure sugar undergoes no change, even when exposed to the 
air ; but if we add to it a little yeast, or the juice of a fruit in 
a state of fermentation, a new action is established ; carbonic 
acid gas is evolved, and alcohol formed. Many sub- 
stances besides yeast, will effect this change, as blood, al- 
bumen, or flour paste, in a state of decomposition. It ap- 
pears, then, that the influence of a ferment depends on the 
condition rather than the kind of matter. Any nitrogenized 
substance capable of undergoing putrefaction produces the 
same effect, and we are to attribute this change, even in the 
juice of fruits, to a small portion of albuminous matter present. 

§ 835. The most reasonable explanation of the action of 
all these bodies is, that it is the influence of their peculiar 
state, (§ 691,) by which the balance of forces in the complex 
molecule is destroyed, and the elements arrange themselves 
to form simpler and more stable compounds. The trans- 
formation of grape sugar into alcohol is very simple ; 1 
equivalent of sugar of grapes (Cj 2^1 4O1 4) contains the ele- 
ments of 2 equivalents of alcohol, 4 equivalents of carbonic 
acid, and 2 of water. 

2 equivalents of alcohol, C4H6O2, Cg H12 O4 

4 " of carbonic acid, CO2, C4 Og 

2 " of water, HO, H2 O2 



1 " of grape sugar, 0^2 Hj4 O 



14 



§ 834. Describe the vinous fermentation. What bodies will produce it ? 
On what does their power depend ? § 835. How may we explain their 
action, (§ 691 ?) Explain on the black-board the decomposition of grape 
sugar. 

36 



422 ORGANIC CHEMISTRY. 

§ 836. Grape sugar is the only kind which is susceptible 
of fermentation ; for although the others readily yield alco- 
hol and carbonic acid, it is found that the first action of the 
ferment is to convert them into grape sugar by the assimila- 
tion of the elements of water. 

Many juices of fruits readily become sour by exposure to 
the air, especially if the quantity of sugar which they con- 
tain, and consequently the portion of alcohol that can be 
formed, is small. But in all these cases, the formation of 
the acid, which is the acetic, is preceded by that of alcohol. 

§ 837. When sugar is mixed with caseine (cheese curd) 
and exposed to a temperature of from 95° to 104°, a pecu- 
liar fermentation takes place, which produces a slimy sub- 
stance that renders the liquid viscid. The other products 
are mannite and a new acid, termed the lactic^ CgHgOg. 
The gummy matter is identical in composition with sugar. 
An equivalent of sugar contains the elements of 1 equiva- 
lent of mannite, 1 of lactic acid, 2 of water, and 1 of oxygen. 
Gas is given off in the decomposition, which is probably 
complicated. Similar products result when the juices of 
beets and carrots ferment at a high temperature. This has 
been termed the viscous fermentation. When caseine or 
any other animal matter in an advanced state of decomposition 
is employed, it induces the alcoholic fermentation ; but at an 
earlier stage of the decay the action is different, giving rise 
to lactic acid and mannite. 

§ 838. When milk is exposed to a temperature from 
95° to 104° it undergoes the vinous fermentation, and forms 
alcohol. It is well known that some nations prepare an 
intoxicating liquor by the fermentation of milk. In this 
process, a small quantity of acid is first formed, which 
converts the lactine into grape sugar. The elevated tem- 
perature promotes the decomposition of the caseine present, 
and thus enables it to produce this fermentation. But milk at 
ordinary temperatures becomes directly acid, without the 
previous formation of alcohol, and we then find that its 
suo^ar is transformed into lactic acid. 



§836. What is said of the fermentation of other sugars? What of 
the souring of the juices of fruits ? § 837. What are the circumstances 
of the viscous fermentation? What are the products? How may they 
be formed from sugar ? What diiferent results are obtained by caseine in 
different states ? §838 Under what circumstances does milk produce 
alcohol ? 



LACTIC ACID. 



423 



^839. Lactic Acid, CeHcOe^^CeH^O^.HO.— This 
acid may be obtained from sour milk. We have mentioned 
it as a product of the fermentation of sugar with caseine, 
and the following modification of that process, is the best 
mode of preparing it. Dissolve fourteen parts of cane 
sugar in sixty of water, and add to it four parts of the curd of 
milk, with about five parts of prepared chalk to neutralize 
the acid formed. This mixture is kept at a temperature of 
77° to 86° F. for two or three weeks, or until it becomes a 
crystalline paste of lactate of lime. This is pressed in a 
cloth, dissolved in hot water and filtered ; the solution is 
then concentrated by evaporation. On cooling, it deposits 
the salt in crystals, which may be purified by recrystallization. 
This process yields about thirteen and a half parts of the 
crystallized lactate, and a small quantity of mannite. 
The reaction is very simple; 1 equivalent of dry grape 
sugar, Ci2Hi2C)i2» contains the elements of 2 equivalents 
of lactic acid, 2 (C^HgOg.) The mannite is the result of 
a secondary decomposition, and with certain precautions, 
lactic acid is the only product. The carbonate of lime 
serves only to neutralize the acid formed. 

§ 840. The lactate of lime may be decomposed by the 
careful addition of oxalic acid, which precipitates the lime, 
and the solution of lactic acid thus obtained, is concentra- 
ted by evaporation, and purified by solution in ether. It 
is a syrupy liquid, of specific gravity 1-315, which is 
strongly acid ,to the taste. Its composition is C6H5O5, 
HO ; the equivalent of water is basic, and can only be re- 
placed by an equivalent of another base. When this acid is 
heated to 482°, a white volatile substance is sublimed, which 
forms brilliant crystals ; it is called lactide. The composi- 
tion of this body is G6H4O4, or the anhydrous acid, minus 
the elements of 1 equivalent of water. It is very slowly 
dissolved by cold water, and changed into lactic acid. 

^841. The lactates contain 1 equivalent of base, and are 
generally soluble and crystallizable. The lactate of lime 
forms beautiful needles, with 5 equivalents of water. The 



What previous action takes place ? What is tlie acid formed in milk 
at ordinary temperatures? § 839. Give the process for lactic acid. Ex- 
plain the reaction. § 840. Describe its properties. What is lactide? 
§ 841. Describe the lactates of zinc and iron. 



424 ORGANIC CHEMISTRY. 

lactate of zinc, ZnO, CgHgOs + SHO, is obtained by de- 
composing a hot solution of lactate of lime by chlorid of 
zinc ; the salt crystallizes on cooling in beautiful colorless 
prisms. The lactate of protoxyd of iron is, like the zinc 
salt, sparingly soluble in cold water, and may be obtained 
by a similar process. It is employed in medicine. 

Starch and gum might be described in connection with 
these bodies, to which they are certainly allied, but as they 
have equally close relations to other substances that 
cannot well be introduced here, they will be reserved for 
another place. 

XVI. METHYLE, C2H3r=:Mt. 

^ 842. This radical has not been isolated, but we have a 
series of compounds like those of ethyle, in which it is sup- 
posed to exist. It forms an oxyd, which acts as a base to 
acids, and a hydrated oxyd analogous to alcohol. This last 
is the source from which we derive all these compounds, and 
is a product of the destructive distillation of wood. 

^ 843. Oxyd of Methyle, Methylic Ether, C2H3, O — 
MtO. — This compound is readily formed by distilling the 
hydrated oxyd with twice its weight of oil of vitriol, when 
the ether is evolved as a colorless inflammable gas, which 
is not condensed by intense cold. Its specific gravity is 
1-617. It is soluble in water, and the solution has an ethe- 
real odor and pungent taste ; the gas is expelled by heat ; 
it is very soluble in alcohol. 

Oxyd of methyle acts as a base, to neutralize the strongest 
acids ; it also unites with some of them to form compounds 
resembling sulphethylic acid. In their chemical relations 
they present a close analogy to the corresponding ones of 
ethyle, (^ 786.) 

^ 844. Hydrated Oxyd of Methyle, Wood Spirit, Py- 
roxylic Spirit, C2H3 0, HO. — The impure acetic acid from 
wood (§ 809) is saturated with quick-lime and distilled, when 
crude pyroxylic spirit passes over. It is afterwards purified 
by repeated distillations. When pure, it is a colorless liquid, 
with a peculiar disagreeable odor and a hot pungent taste. 

§ 842. What are the composition and properties of methyle? § 843. 
Describe the preparation and properties of the ox3'd. § 844. How is 
methyhc alcohol obtained? Describe its properties stud uses. 

* From the Greek, methu, wbie, hule, wood, corresponding to wood- 
spirit 



METHYLE. 425 

It has a specific gravity of -798, boils at 152° F., and 
burns with a peculiar bhie flame. Like alcohol, it mixes in 
all proportions with water. It is used in the arts for dis- 
solving resins and making varnishes, but as found in com- 
merce is always impure. The pure methylic alcohol has 
lately acquired some celebrity in the treatment of phthisis, 
under the improper name of wood naphtha. 

Oxyd of methyle has lately been found to be a direct pro- 
duct of vegetable life. The oil of wintergreen, Gaultheria 
procurnhenSj is a salicylate of the oxyd of methyle, (^ 776.) 
When this compound is heated with a solution of potash, a 
salicylate of the alkali is formed, and pure hydiated oxyd 
of m^ethyle distills over. Methylic alcohol dissolves caus- 
tic baryta, and forms with it a crystalline compound. 

§ 845. Chlorid of Methyle, Mt'Cl. — This is obtained by 
distilling wood spirit with common salt and sulphuric acid. 
It is a colorless gas, of specific gravity 1731, and may be 
collected over water. It has an ethereal odor and sweet 
taste. 

Compounds of methyle with iodine, fluorine, cyanogen, 
and sulphur, may be formed in the same manner as the cor- 
responding ones of ethyle. The fluorid, Mt F, is gaseous, 
the others are liquids. The sulphur compound, MtS^H, is 
quite analogous to mercaptan, (^ 793.) 

§ 846. Sulphate of Oxyd of Methyle, Mt SO3.— This sub- 
stance is formed by distilling a mixture of wood spirit with 
8 or 10 parts- of sulphuric acid. The sulphate of methyle 
collects in the receiver as a tasteless oily fluid, with an alli- 
aceous odor. It has a specific gravity of 1-324, and boils 
at 370°. It is insoluble in water, but is rapidly decomposed 
by it at 212°, being resolved into hydrated oxyd of methyle 
and sulphomethylic acid. When distilled with any salt, as 
chlorid or cyanid of potassium, it forms a compound of the 
radical with methyle, and a sulphate of the alkali. All the 
other salts of methyle may be formed in the same manner. 
Nitrate of oxyd of ethyle, Mt NO5, is obtained by distilling 
methylic alcohol with nitrate of potash and oil of vitriol. 



What is wood naphtha? In what plant is oxyd of methyle found? 
§ 845. Describe the chlorid of methyle. What other compomids are 
noticed? § 846. Describe the preparation and properties of the sulphate. 
Describe the nitrate and give its composition. '^ 

36* 



426 ORGANIC CHEMISTRY. 

It is a heavy oily fluid, and its vapor, w^hen heated to about 
250°, explodes with great violence. 

^847. Oxalate of Oxyd of Methyle, MlO,C203.— This 
compound is readily formed by distilling a mixture of equal 
parts of wood spirit, oxalic acid, and oil of vitriol. A liquid 
collects in the receiver, which when exposed to the air, soon 
evaporates, leaving the oxalate of methyle in fine crystalline 
plates. It has a fragrant odor, fuses at 124°, and is readily 
soluble in alcohol and water. The aqueous solution is rap- 
idly decomposed into oxalic acid and methylic alcohol. 

§ 848. Sulphomethylic acid, MtO 2SO3, HO, is formed 
in the same manner as the sulphethyhc. The sulphomethy- 
late of baryta forms beautiful tabular crystals which effloresce 
in the air; their composition is MtO 2SO3, BaO + 2HO. 
The sulphomethylic acid is obtained from this salt by sul- 
phuric acid ; it is very soluble in water and forms minute 
silky crystals. It is decomposed by heat in the same man- 
ner as sulphethylic acid, yielding metbylic ether. 

When methylic alcohol is submitted to oxydizing agents, it 
gives rise to a series of compounds v/hich appear to contain 
a new radical, formyle. It is formed from methyle by the 
remov^al of 2 equivalents of hydrogen, precisely as acetyle 
is derived from ethyle. 

XVII. FORMYLE, C2H. Sj/mbol, Fo. 

§ 849. Formic Acid, C2HO3, HO = F0O3HO.— This acid 
was first noticed as a secretion of the red ant, {Formica rufa,) 
and hence the name, formic acid. It is produced by the 
action of platinum black on methylic alcohol, by a process 
of oxydation similar to that for producing acetic acid, (§ 807,) 
but is best prepared by the oxydation of sugar or other or- 
ganic substances. 800 grains of bichromate of potash are 
dissolved in 7 ounces of water, and 300 grains of sugar are 
then added. The mixture is placed in a retort, and 1 fluid 
ounce of sulphuric acid is added very slowly, to prevent any 
violent reaction. The mixture is now distilled with a gentle 
heat, until 3 ounces of formic acid are obtained. From this 



§ 847. How is the oxalate obtained, and what are its properties ? 
§ 848. Describe the sulphomethylic acid. Give the formula for sulpho- 
methylate of baryta. What is the action of oxydizing agents on the 
methylic compounds? What is the composition of formyle ? § 849. By 
what animals is formic acid secreted ? How is it best obtained ? 



FORMYLE. 427 

we may form salts, which, when decomposed, afford a 
strong acid. 

^ 850. The pure hydrated acid, F0O3, HO, is obtained by 
decomposing dry formiate of lead by sulphureted hydrogen. 
The action is aided by a gentle heat, and the acid distills 
over. It is a colorless liquid, of specific gravity 1*235, 
which fumes in the air, and has a powerfully pungent odor. 
It boils at 212° F., and at 32° crystallizes like acetic acid in 
shining plates. In the pure state it is powerfully acid, and 
very corrosive, instantly blistering the skin. When this acid, 
or any of its salts, is heated with strong sulphuric acid, it is 
immediately decomposed, with the escape of pure carbonic 
oxyd. The elements of 1 equivalent of formic acid, F0O3 
HO = C204H2=:2CO + 2HO. The affinity of sulphuric acid 
for water promotes this decomposition. On account of the 
readiness with which it is decomposed, formic acid or its 
saUs precipitate the noble metals from their solutions by a 
gentle heat, carbonic acid being evolved. 

^851. Formic acid formiS with bases, salts which are sol- 
uble, and have a general resemblance to the acetates, from 
w^hich their reaction with salts of silver or mercury will 
distinguish them. The formiate s of potash and soda are very 
soluble salts.' The formiate of ammonia undergoes an inter- 
esting decomposition by heat. When its vapor is passed 
through a red-hot tube, it is resolved into hydrocyanic acid 
and water, C2HO3, NH40=.C2N H + 4H0. 

The for miates of mercury and silver are sparingly soluble 
crystalline salts ; when their solutions are gently warmed 
they are completely decomposed, with the separation of me- 
tallic mercury or silver, and the escape of carbonic acid. 

Compounds of Formyle with Chlorine^ Bromine, and Iodine. 

§ 852. The action of chlorine on various bodies of the 
ethyle and methyle series, gives rise to a number of com- 
pounds, which are supposed to contain this radical. In this 
way we obtain FoCl and F0CI2. Perchlorid of formyle or 
chloroform is obtained by distilling alcohol or wood spirit with 

§ 850. Describe the pure acid. Hovi^ is it decomposed by sulphuric acid ? 
Explain the reaction. How does it act with salts of silver and gold ? 
§ 851. What salts do the fonniates resemble? Describe the decomposi- 
tion of the formiate of ammonia. § 852. Describe the preparation and 
properties of perchlorid of formyle. 



428 ORGANIC CHEMISTRY. 

a solution of 2 or 3 parts of chlorid of lime in 24 of water. 
It is a heavy oily fluid, which is nearly insoluble in water, 
has a specific gravity of 1-48, and boils at 141°. It has a 
very sweet and pungent taste, with a fragrant ethereal odor, 
and its alcoholic solution is largely used in medicine, under 
the name of chloric ether. 

§ 853. Perbromid of formyle^ FoBrg, resembles the last 
compound, and the periodid, F0I3, forms golden yellow 
crystalline scales. All of these are immediately decomposed 
by an alcoholic solution of potash, yielding a compound of 
the salt radical with potassium and formiate of potash. Thus 
FoCl3 + 4KO = 3KCl-f-Fo03, KO. 

When perchlorid of formyle is exposed to the action of 
chlorine, the hydrogen is replaced, and we obtain C2Cl,Cl3 
= 62014, a bichlorid of carbon. The action of chlorine on 
the compounds of methyle and formyle is very complex, 
and similar to that which takes place with those of ethyle 
and acetyle. 

XVIII. AMYLE, CjqH;^!. Symbol, Ayl. 

§ 854. In the distillation of spirit made from potatoes, the 
last portions of the alcohol are rendered milky by the pres- 
ence of a peculiar liquid, which separates on standing. 
This substance forms a class of compounds having a close 
affinity to those produced from alcohol, and is supposed to 
be the hydrated oxyd of a compound radical, analogous to 
ethyle, to which the name of amyle has been given. The 
oxyd of amyle or amylic ether has been formed, but its 
properties are not well known. 

^855. Hydrated Oxyd of Amyle ^ CioHjjO, HO, ^my- 
lic Alcohol^ Potatoe Oil, FuseloeL— This is a frequent pro- 
duct of the alcoholic fermentation, but the conditions of its 
formation are not well understood. When pure, it is a col- 
orless liquid, which is insoluble in water, boils at 269°, 
and has a specific gravity of -818. It has a burning taste, 
and a disagreeable odor, which produces coughing and dis- 
tressing nausea. 



How is it used in medicine, and under what name? § 853. Describe 
the periodid. How are these decomposed by potash 1 Explain the reac- 
tion on the black-board. What is the result of the action of chlorine on 
perchlorid of formyle ? § 854. What is the composition of amyle ? 
*§ 885. What names are applied to amylic alcohol? Describe its proper- 
ties. 



VALERYLE. 429 

§ 856. The chlorid of amyle, AylCl, is a heavy oily liquid ; 
the bromid, iodid, cyanid, and sulphuret have been obtained. 
It forms a compound which corresponds to mercaptan. The 
liyponitrite^ oxalate, and acetate, are prepared by processes 
similar to those which afford the corresponding ethyle com- 
pounds. They are decomposed by alkalies. 

^ 857. The sulphamylic acid, Ayl0 2S03, HO, is pre- 
pared in the same manner as the sulphethylic acid, which 
it closely resembles in its properties. 

When amylic alcohol is dropped upon platinum-black, ox- 
ydation takes place, and valerianic acid is formed. The re- 
action is similar to that which produces acetic acid from al- 
cohol ; the amyle loses 2 equivalents of hydrogen, and ac- 
quires 3 of oxygen. We may suppose the existence of a 
radical, valeryle, which is analogous to acetyle. 

XIX. VALERYLE, CjoH^Q- Symbol, YL 

^ 858. Valerianic Acid; Valeric Acid, CjoHgOg, H0 = 
VIO3, HO. — This acid is the most important derivative of 
the amylic compounds. We have already mentioned its 
formation by the aid of platinum-black. It is also obtained 
by heating amylic alcohol with hydrate of potash, when 
hydrogen is evolved and valerianate of potash formed. 
This acid is identical with that which exists in the roots of 
valerian, Valeriana officinalis, and in one or two other 
plants. It may be obtained from these by distillation with 
water. Valerianic acid is best prepared by distilling the 
valerianate of potash with dilute sulphuric acid. It is a 
colorless fluid, scarcely soluble in water, and has a pungent 
acid taste, with a peculiar odor. The medicinal virtues of 
valerian depend upon this acid, which has lately been ex- 
tensively employed in medicine. It is principally used in 
combination, as the valerianate of zinc, which is obtained by 
neutralizing the acid with carbonate of zinc, and crystallizes 
in line pearly scales. 

^ 859. When amylic alcohol is distilled with anhydrous 



§ 856. What other compounds are mentioned ? ^ 857. What is the 
composition of sulphamylic acid? What is the result of the oxydation of 
amylic alcohol? §858 What is the composition of valeryle? What 
native source of this acid is mentioned? Describe its properties. What 
is its use ? § 859. What is the composition of amilene ? 



430 ORGANIC CHEMISTRY. 

phosphoric acid, it is decomposed, and a volatile liquid is 
produced, which is named amilene. This is formed by the 
abstraction of the elements of 2 equivalents of water, a reac- 
tion analogous to that by which alcohol furnishes olefiant 
gas, with which amilene is isomeric, being CiqHjq. 

XX. CETYLE, C32H33. Symbol, Ct. 

This radical is su})posed to exist in ethal, a peculiar fatty 
matter derived from spermaceti, which is a hydrated oxyd of 
cetyle. 

^ 860. Hydrated Oxyd of Cetyle, Ethal C32H33O, HO 
nrCtO, HO. — When spermaceti is digested with a hot so- 
lution of potash, we obtain a mixture of ethal with ethal- 
ate of potash. It is a white volatile substance which fuses 
at 118°. It is readily soluble in alcohol and crystallizes 
from the solution on cooling. It does not dissolve in boiling 
water, but distills over with its vapor. 

§ 861. Chlorid of Cetyle, CgsHsgCl^CtCL— When hy- 
drated oxyd of cetyle is distilled with perchlorid of phos- 
phorus, chlorid of cetyle is obtained as a heavy oily fluid. 
The residue of this process is said to contain a phosphate of 
oxyd of cetyle. 

Sulphoceiylic Acid, CtO 2SO3, HO. — This acid is ob- 
tained by heating a mixture of ethal and sulphuric acid. It 
is very analogous to sulphethylic acid. 

^ 862. When ethal is heated to a temperature of 400° in 
contact with caustic potash, hydrogen is evolved and a new 
acid is formed ; the reaction is precisely similar to that by 
which acetic and valerianic acids are formed from alcohol 
and potatoe oil ; and we may, by analogy, suppose a new rad- 
ical, C32H31, which mdij he wd^meAe thalyle. We have not 
discovered any compounds of this radical, but that corres- 
ponding to acetic acid. 

§ 863. Ethalic Acid, C32H31O3, H0=rCt03, HO.— 
This acid is formed by the oxydation of the hydrated oxyd 
of cetyle. It also exists in spermaceti, combined with the 



What is the formula of cetyle? § 860. How is ethal obtained? Give 
its composition and properties. § 861. Describe the chlorid and its com- 
position. Give the composition of sulphocetylic acid. §862. What is the 
result of its oxydation? How isethalyle formed? § 863. How is ethalic 
acid formed ? 



CETYLE. 431 

oxyd of cetyle. This acid is crystallizable and volatile ; it 
is insoluble in water, but dissolves readily in alcohol, and 
its solution reddens litmus paper. It presents a close anal- 
ogy to a class of fatty acids, hereafter to be described, but is 
related in its formation to the preceding compounds. Sper- 
maceti is the ethalaie of the oxyd of cetyle. When we distill 
ethal with anhydrous phosphoric acid, we obtain a liquid 
called cetene, C32H32, which is isomeric with olefiant gas. 

^ 864. The radicals ethyle, methyle, amyle, and acetyle, 
form a finely characterized natural group, connected by well- 
marked affinities. The number of atoms of hydrogen is al- 
ways one more than that of the carbon. The oxyds of the 
radicals consequently contain the elements of 1 equivalent 
of water, plus a carburet of hydrogen, whose formula is a 
multiple of C H ; and are resolved into these, by the action 
of bodies which have a strong attraction for water, aided by 
heat; thus AeO = C4H4 + HO. The compounds of these 
radicals with chlorine bromine, and sulphur ; of their oxyds 
with water and various acids ; their union with 2 equiva- 
lents of sulphuric acid to form a new and peculiar acid, and the 
singular bodies of the mercaptan class, all demonstrate the 
close affinity which unites the members of this group. 

The results of their oxydation are not less characteristic ; 
all of them lose 2 equivalents of hydrogen, and form com- 
pounds which are derived from new radicals ; these, as a re- 
sult of their mode of formation, have a number of equivalents 
of hydrogen, less by one, than that of the carbon; they 
unite with 3 equivalents of oxygen, to form strong acids. 

^ 865. In a group of simple or compound radicals the per- 
fection in the development of the typical characters is inverse- 
ly as the equivalent number, or weight, of the atom. In 
methyle, which has an atomic weight of 14, we find the 
characters of this group exhibited in the greatest fullness, 
and the stability of the compound is apparently greater than 
in ethyle, whose equivalent is 29. We thus perceive a 
transition from methyle to ethyle, amyle, and cetyle ; this 
last has a high equivalent, and exhibits much less perfectly 
those characters which define the group. We have not yet 

Describe its composition and properties. What is the composition of 
spermaceti? How is eetene obtained, and what is its formula? § 864. 
What analogy in composition is seen in the precedintr jrroup of radicals? 
What do their oxyds contain ? How is thisanaloory shown? How in the 
results of their oxydation? §865. What proposition is here anuouuced ? 
Illustrate it by methyle, &c- 



432 ORGANIC CHEMISTRY. 

obtained the carbohydrogen, C2H2, from the methyle com- 
pounds. This is attributable to that permanence which 
belongs to a comparatively simple molecule. 

The acids derived from this group exhibit a beautiful gra- 
dation of characters from the very soluble and corrosive for- 
mic and acetic acids, to the insoluble crystalline ethalic ; 
the valerianic acid is intermediate in its properties. The 
two last radicals, with their acids, present a close analogy to 
the fats, and in their properties connect the members of this 
group with those of that class of bodies. 

III. ORGANIC ACIDS. 

^ 866. Besides the acids already described as the deriva- 
tives of known organic radicals, there are a large number of 
acids, many of which are very important, that we have 
not as yet been able to classify. We can notice only a few 
which are of the most interest. In expressing the com- 
pounds of these acids, we employ as a symbol, the initial 
letter with a dash over it ; thus tartaric acid is T- When 
there is more than one with the same initial, we combine 
with it some other characteristic letter, as ci, for citric 
acid. 

§867. Citric Acid, Ci2H50^ 1, 3H0 = Ci, 3H0.— This 
acid exists in the juices of the lemon, orange, and many 
other fruits. By saturating the juice with chalk, an insolu- 
ble citrate of lime is obtained. This is decomposed by an 
equivalent of dilute sulphuric acid, which forms an insoluble 
sulphate of lime, while the citric acid remains in solution 
and is purified by crystallization. It forms large crystals 
which belong to the trimetric system ; it is very soluble in 
water and has a strong but pleasant acid taste. It is tri- 
basic, and its salts are unimportant. 

§ 868. Aconitic Acid, C4H03,H0=Xt,H0.— This is a 
monobasic acid ; it is formed when citric acid is exposed to a 
heat of about 300°. It is found in the Aconitum napellus, 
and also in several species of JEquisetu?n. When decomposed 
by heat, it yields two new acids, the itacoiiic and citraconic. 

§ 869. Tartaric Acid, CgH^Oio, 2H0=:T^, 2H0.— This 

What is said of the gradation of characters which connect these to an- 
other class of bodies': § 866. What symbol is used for the organic acids? 
§ 867. How is citric acid obtained ? Describe its composition and prop- 
erties. § 868. What is said of aconitic acid ? 



ORGANIC ACIDS. 433 

acid is very common in the juices of fruits. It is present in 
that of the grape, as an acid tartrate of potash, and after fer- 
mentation, is deposited in crusts. This is known as crude 
tartar or argoU ^nd is quite impure ; it is decomposed by 
chalk to form a tartrate of lime, which is then treated with 
sulphuric acid in the same manner as the citrate. This 
acid forms fine crystals, which are modified rhombic prisms ; 
they are very soluble in water and alcohol, and have a pleas- 
ant acid taste. 

^ 870. Tartaric acid is bibasic and forms two classes of 
salts. Those in which but 1 equivalent of the water is re- 
placed by another base, are acid. The most important of 
these is the salt of potash. 

Bitartrate of Potash, Cream of Tartar^ Ta, KO HO. — The 
source of this has been already mentioned. It is purified by 
solution, and is usually obtained as a white crystalline 
powder. It is very slightly soluble in cold water, has a 
pleasant acid taste, and is extensively used in medicine and 
in dyeing. 

^871. The neutral tartrates have very often two bases. 
The tartrate of potash and ^ocZa, Ta, KO NaO, forms very 
large prismatic crystals, and is well known in medicine un- 
der the name of Rochelle salt. The neutral tartrate of pot- 
ash, Ta, 2K0, or soluble tartar, is also used medicinally. 
The tartrate of potash and antimony, Ta, KOSbOg, is 
obtained by boiling the acid tartrate of potash with oxyd of 
antimony. It -forms large transparent crystals, and is the 
well known tartar emetic. Tartaric acid combines with 
oxyd of ethyle to form tartaric ether and tartrethylic acid. 

^ 872. When heated, tartaric acid gives rise to several 
new acids which are derived from it, by the abstraction of 
the elements of water. The composition of these acids, 
and their relation to each other, may be expressed as fol- 
lows : 



Tartaric acid, 


Cs H40jo,2HO. 


Tartralic acid, 


Ci2HeOi„2HO. 


Tavtrelic acid. 


Ci6H302o,2HO. 


Anhydrous tartaric acid. 


C4 H2O,. 



§ 869. What is the source of tartaric acid? Describe the preparation. 
§ 870. Why does it form two classes of salts? Describe the acid tartrate 
of potash. §871. What is the coiiiposition of Rochelle salt- What of 
tartar emetic ? § 872. What changes does this acid undergo by heat? 

37 



434 ORGANIC CHEMISTRY. 

This last is insoluble in water, alcohol, and ether, but 
w.hen long boiled with water, is gradually converted into 
tartaric acid, a change which all the other acids in this 
series undergo. Tartaric acid, by a still stronger heat, pro- 
duces a volatile crystallizable acid, the pyrotartaric, C5H3 

Og.HO. 

^ 873. Racemic Acid, Pyrotartaric Acid, C4H2O5, HO 
= R, HO. — This acid is frequently associated with the tar- 
taric acid in the juice of grapes, and it is separated from it 
by its different solubility. It has a very close resemblance 
to tartaric acid : it forms a sparingly soluble salt with pot- 
ashj and yields the same products by heat. Its composition 
in 100 parts is the same. It differs from tartaric acid, 
however, in being monobasic, and does not form double 
salts with alkaline bases. The double racemate of potash 
and water, 2C4H0O5, KO HO, is isomeric with the acid 
tartrate, C8H4OJ q, KO HO. We cannot, however, ob- 
tain a double racemate of potash and soda corresponding 
to Rochelle salt, and in all its salts we see a difference of 
properties, notwithstanding their close resemblance. 

^ 874. Malic Acid, C8H4O8, 2H0=:M, 2H0.— This is the 
acid of the apple and many other fruits. It is found in large 
quantities in the stems of the garden rhubarb, which of- 
fers the best source of it. It is very soluble in water and 
alcohol, and crystallizes with difficulty ; its solution has an 
agreeable acid taste. This acid is bibasic, and forms two 
classes of saUs. The acid malate of ammonia, CgH^Og 
NH4O, HO, forms large and beautiful crystals : the malate 
of lead, C8H408,2PbO, is obtained as a white precipitate, 
which if left in the liquid, soon changes into delicate crystals. 

When malic acid is exposed to heat, it is decomposed ; a 
volatile acid passes over, and a crystalline residue remains 
in the retort. This is the fumaric acid, and is identical with 
an acid which occurs in the Fumaria offcinalis ; its for- 
mula is C4HO3HO. It is sparingly soluble in cold water. 
The volatile product of this decomposition is maleic acid, 
which is soluble and differs entirely from the fumaric. 
Heat gradually changes it into that acid. Its composition is 
C8H206,2HO, or double the equivalent of the fumaric, 
which is isomeric with aconitic acid, (^ 868.) The student, 

§ 873. What are the characters of racemic acid? How is it related to 

tartaric acid, and how different? § 874. What are the sources of malic 

acid ? What is the composition of malate of lead ? What changes does 
it undergo by heat ? 



ORGANIC ACIDS. 435 

by comparing the formulas, will readily perceive the reaction 
by which the maleic is derived from the malic acid. ^ 

^ 875, Tannic Acid. — Many plants contain a peculiar 
substance known as the astringent or tanning principle, 
which is characterized by the property of precipitating animal 
gelatine, and producing, with persalts of iron, a bluish-black 
precipitate. This substance is found abundantly in the bark 
of several species of oak and in nut-galls. Several other 
substances, as the kino and catechu^ which are extracts from 
vegetables, contain something resembling the astringent 
principle of the oak, but which differs from it in the color 
of its precipitate with iron. Some chemists have described 
these as distinct, but they are more probably the quercitannic 
modified by the presence of other acids. The question is 
still undecided, and we will describe only the tannic acid of 
the oak. 

^ 876. Quercitannic Acid, CigHsOg, 3H0 — Qt, 3H0.— 
This substance is best obtained from nut-galls, which are 
excrescences produced by an insect on the bark of a 
species of oak. The following process by Pelouze, gives 
us the acid in a state of purity. The gall-nuts in 
coarse powder are placed in the upper vessel repre- 
sented in the figure, the mouth of which is pre- 
viously stopped by a piece of linen. A quantity of 
washed ether (§ 785) is then poured over them, 
which slowly filters through, and collects in the 
lower vessel,. where it separates into two layers. 
The lower is an aqueous solution of pure tan- 
nic acid, while the lighter fluid is ether, holding in 
solution the coloring matter of the gall-nut and 
other impurities. The ether used in this process 
contains about -^^ of water, which dissolves the tan- 
nic acid to the exclusion of all other substances. 
The solution is evaporated in a vacuum with sul- 
phuric acid, (§ 122.) It is a light, porous mass, 
of a pale-yellow tint. It is very soluble in water ; 
the solution has a purely astringent taste, and red- 
dens litmus paper. Tannic acid forms salts which 
have not been much studied. Those of the alkalies are 



§875. What are the characters of tannic acid? From what is it deri- 
ved ? § 876. How is it prepared ? Explain the nature of the process. 
What are the uses of the pertannate of iron 1 



436 ORGANIC CHEMISTRY. 

soluble. The tannate of sesqiiioxyd of iron, Fe2 03, 3Qt, is 
\j^ basis of black dyes and writing ink. 

^ 877. Gallic Acid, C7H032HOr=G,2HO.— This is 
best obtained by exposing a mixture of pulverized gall-nuts 
and water to the air, for two or three months. A pecu- 
liar fermentation ensues, and the tannic is converted into 
gallic acid. It is readily dissolved out by boiling water, which 
deposits it on cooling. Gallic acid forms small silky crys- 
tals, which have an acid and astringent taste. It does not 
precipitate gelatine, and the black pergallate of iron loses 
its color when heated. Tannic acid is converted into gallic 
acid by the action of both acids and alkalies, but the nature 
of the change is not well understood. 

§878. Mecomc^ci^, Ci4H0]i, 3H0 = Me, 3H0.— This 
tribasic acid occurs in the juices of the poppy, combined 
with morphine, a vegetable alkaloid. It is obtained as 
a white crystalline substance, readily soluble, and forming 
a large number of salts. When boiled with hydrochloric 
acid it loses the elements of carbonic acid, and is converted 
into comenic acid. Its decomposition by heat and alkalies 
presents several interesting reactions, which are described 
in the larger works. 

§ 879. Kinic Acid. — This exists in the bark of sev- 
eral species of Cinchona, as a soluble kinate of lime, which 
when decomposed, affords the acid in large crystals resem- 
bling tartaric acid. Its composition is perhaps Cj 4Hii^0ii, 
HO, but this is uncertain. When kinic acid or a kinate 
is distilled with dilute sulphuric acid and peroxyd of man- 
ganese, a substance called kinone is obtained. It forms 
beautiful golden-yellow crystals, which are very soluble and 
volatilize with a pungent odor. The composition of kinone 
is C25H8O8. When acted upon by reducing agents, as sul- 
phurous acid, it combines with 2 equivalents of hydrogen to 
form C25H10O85 which crystallizes in beautiful prisms with 
a golden-green metallic lustre. Byan excess of sulphurous 
acid, we obtain a compound with 4 equivalents of hydrogen, 
Avhich forms white hexagonal prisms. This substance, if 



§877. How is gallic acid prepared? Describe its properties. §878. 
Jn what does meconic acid occur? How is it decomposed by hydrochlo- 
ric acid ? § 879. What is the source of kinic acid ? How is kinone 
formed ? Describe its properties and the composition of the beautiful 
green compound. How is it formed from the white substance ? 



FATTY SUBSTANCES. 437 

mixed with kinone, gives up 2 equivalents of hydrogen, 
and the beautiful green compound is formed. Woehler, who 
has carefully studied these reactions, has described a num- 
ber of compounds derived from these by substitution, which 
contain sulphur and chlorine. 

IV. FATTY SUBSTANCES. 

^ 880. This term is applied to a large class of substances 
both of animal and vegetable origin, which are insoluble in 
water, combustible, and volatile only at high temperatures, 
with decomposition. They also agree in their chemical 
characters, and constitute a group of bodies so closely al- 
lied, that they may be conveniently considered together. 
These substances vary much in fusibility ; some are fluid 
at common temperatures, while others require a temperature 
of 130° for their fusion. This diversity is due to the fact 
that they are mixtures, in varying proportions, of two or 
three fats which differ in fusibility, and which may gener- 
ally be separated from each other, by taking advantage of 
this property. 

§ 881. When we act upon these bodies by a caustic al- 
kali, or some- other base, with the aid of heat, we find that 
they are separated into peculiar acids, which combine with 
the alkalies to form salts, (soaps,) and a sweet soluble sub- 
stance which is called glycerine. From this reaction we 
conclude that glycerine acts as a base to the acids, and that 
these compounds are salts of glycerine. 

^ 882. Glycerine,^ CgH^O^, HO. — This is best prepared 
by heating a mixture of olive oil withoxyd of lead and water ; 
the acids combine with the oxyd to form insoluble salts, and 
the glycerine separates. It is obtained pure by precipita- 
ting the dissolved lead with sulphureted hydrogen, and evap- 
orating the solution in vacuo. It forms a syrupy liquid 
which has a very sweet* taste, but is not susceptible of the 
vinous fermentation. It combines with sulphuric acid to 
form a compound acid analogous to the sulphethylic. When 

§ 880. What are the characters of the fats? Why do they differ in 
fusibility? § 881. How do they act with bases? What is the conclusion 
from this? § 882. How is glycerine obtained? What are its properties? 

* From the Greek, glukus, sweet. 
37* 



438 ORGANIC CHEMISTRY. 

heated with substances having a strong attraction for water, 
it is changed into acroleine, which is C6H4O2. This sub- 
stance has a powerful pungent odor, similar to that given off 
by fats when decomposed by heat. The evolution of acrole- 
ine when any oil is distilled, is a proof that it contains gly- 
cerine. 

^ 883. StearineJ^ — Animal tallow contains a large portion 
of stearine, which is best separated by treating the fat with 
several times its bulk of hot ether. The stearine crystallizes 
on cooling. It is a white friable mass which melts at 130° F., 
and is almost insoluble in alcohol. When heated with a so- 
lution of caustic alkali, it yields glycerine and stearic acid. 
This acid is very soluble in alcohol and ether, but insoluble 
in water. Its solution reddens litmus paper, and decomposes 
alkaline carbonates. Its melting point is 167°. The com- 
position of this acid is CggHcgO^, 2H0 ; it combines with 
oxyd of ethyle to form a neutral and acid stearate. The 
neutral stearates of the alkalies with 2 equivalents of base, 
are soluble in water, and are proper soaps. The stearates 
of the other bases are obtained by double decomposition ; 
they are fusible and insoluble in water. 

\ 884. Margarine.^ — This constitutes a large portion of 
many fats, and is obtained from the ethereal solution by 
evaporating until the ether is expelled, and then absorbing 
the fluid oil by blotting-paper. When pure, it closely re- 
sembles stearine, but is more soluble in cold ether, and fuses 
at 116°. With alkalies, it yields glycerine and margaric 
acid. This acid melts at 140°, and has a general resem- 
blance to stearic acid, which extends also to its salts. Its 
formula is CggHegOg, 2H0. This, it will be seen, differs 
from stearic acid only in 1 equivalent of oxygen, and we 
can readily convert stearic into margaric acid, by heating it 
with nitric acid. 

§ 885. Oleine. — This constitutes the liquid part of fats ; it 

How is acroleine formed? §883. Describe stearine. Describe stearic 
acid. What is the constitution of its salts ? § 884. How is margarine 
obtained, and what are its characters ? Describe margaric acid. From 
what is the name derived? How is it related to stearic acid ? 

* The different portions of fats are denominated stearine and oleine, 
from the Greek, stear, tallow, and elaion, oil. 

t From the Greek, margarites, a pearl, in allusion to the pearly lustre 
of its acid. 



FATTY SUBSTANCES. 439 

is obtained from olive oil by cold, wbich causes the marga- 
rine to crystallize out. It is lighter than water, tasteless and 
inodorous. When digested with alkalies it yields, like other 
fat, glycerine and oleic acid. This resembles oleine itself, 
and is without taste or odor ; it rapidly absorbs oxygen from 
the air. Its composition is C3gH3303,H0. When oleic 
acid or oleine is decomposed by heat, it yields the sebacic 
acid, which is Cj 0^303, HO. 

§ 886. The compounds of these acids are very important, 
and constitute the bodies generally known as soaps. These 
are mixtures of oleate, margarate, and stearate of potash or 
soda, being formed from the saponification of mixed fats by 
these alkalies. The soft soaps contain potash, and the hard 
ones soda. All these compounds are readily decomposed by 
acids, which combine with the alkali and liberate the fatty 
acid. When we mix a solution of soap with the soluble 
salt of any other base, we obtain a precipitate which is an 
insoluble combination of the fatty acid with the base. Hence 
the power of salts of lime or magnesia to render water hard. 
The compounds of these acids with the oxyd of lead, consti- 
tute the lead plaster, or diachylon, so much used in surgery. 
A mixture of scearic and margaric acids, obtained by sap- 
onifying animal fats with lime, and decomposing the insolu- 
ble soap by hydrochloric acid, has been employed in the 
manufacture of candles. By a peculiar process the oleine 
of lard is now separated from the stearine and margarine, 
and both these products are extensively used, under the 
names of lard oil and stearine. 

§ 887. When margaric acid is digested with nitric acid, 
it is slowly oxydized, and gives rise to several new products. 
The most important are suberic and succinic acids. The 
suberic acid, which is a sparingly soluble substance, is also 
formed by the action of nitric acid on cork. The succinic 
acid is the principal product of this reaction ; it exists in 
amber, and it may be obtained from it by distillation. It is 
volatile, soluble in water, and has the formula C4H2O3, HO. 

^ 888. Palm Oil. — This substance, which is largely used 

§ 885. What is oleine? What is the composition of olic acid ? What 
is the action of heat upon it? §886. What is the nature of soaps? 
What is the reaction of these with salts of other bases? What is the 
composition of lead plaster? § 887. What is the action of nitric on mar- 
garic acid ? What is said of suberic acid ? What other source is tli^re 
of Buccinic acid ? Describe tlie acid. 



440 ORGANIC CHEMISTRY. 

in the manufacture of soap, is obtained from the nuts of the 
Elais guinensis, a native of the western coast of Africa. It 
has a yellow color and fragrant odor, and. is a mixture of 
oleine with a peculiar solid fat called palmatine. This, 
when saponified, yields palmitic acid, which closely resem- 
bles the margaric. The fats of the cocoa-nut and nutmegs 
contain substances resembling palmitine in their general 
properties. 

^ 889. Butter. — This substance is a mixture of several 
fats ; the one to which it owes its peculiar agreeable fla- 
vor is called hutyrine. This when saponified is resolved, 
like other bodies of this class, into glycerine and a new 
acid, the butyric. This acid has lately acquired a new in- 
terest by the discovery that it can be artificially formed 
from the fermentation of sugar or starch. The mixture di- 
rected for the preparation of lactic acid (§ 839) is exposed 
for some weeks to about 90° F., when the lactate first 
formed slowly dissolves, and butyrate of lime is found in its 
place. From this, the pure acid may be obtained by distilla- 
tion with hydrochloric acid. The butyric acid is a colorless, 
volatile, oily liquid, little soluble in water ; it is strongly acid 
and has a penetrating odor. Its composition is CgHyOa, 
HO. 

The butyrate of oxyd of etJiyle, AeO, CgH^Og, is easily 
formed by heating a mixture of butyric acid and alcohol with 
sulphuric acid. It is a limpid fluid, having an odor like that 
of pine-apples. The butyrate of glycerine, or butyrine, is said 
to be formed, when we substitute glycerine for alcohol in the 
above process. 

^ 890. EnantJiic Acid, C14H13O2, HO. — This acid is an 
accidental product of the vinous fermentation. The peculiar 
odor of wine is due to its compound with oxyd of ethyle.* 
Enanthic acid is a fusible solid, which is insoluble in water 
and resembles the other fatty acids. 

Wax. — This body is not a fat, as it does not admit of sa- 
ponification. It appears to consist of two distinct bodies, ce- 



§ 8.88. What is the composition of palm oil ? § 889. Of what is but- 
ter composed ? What is the result of saponification of butyrine ? How is 
butyric acid artificially formed? What are its characters and composi- 
tion ? Describe the butyrate of ethyle. § 890. What is enanthic acid ? 

* * Hence the name, from the Greek, oinost wine. 



VOLATILE, OR ESSENTIAL OILS. 441 

rine and myricine, but has not been much studied. When 
heated with nitric acid, it yields products similar to those af- 
forded by margaric acid. 

§ 891. Athamantine. — This is a crystalline substance 
found in the roots of the Athamanta oreoselinum. It is in- 
soluble in water, readily soluble in ether, very fusible, and 
not volatile without decomposition. By the action of acids 
or alkalies, it is decomposed into valerianic acid, and a new 
substance, oreoseline, which takes the place of glycerine. 
Spermaceti has been described (§ 860) as an analogous body, 
which affords ethalic acid and ethal by the action of alka- 
lies. These substances have the general properties of the 
fats, but differ in not containing glycerine. 

V. VOLATILE, OR ESSENTIAL OILS. 

§ 892. These names are applied to a large class of pro- 
ducts which are obtained by distilling vegetables with w^ater. 
They generally possess, in a high degree, the peculiar odor 
of the plants from which they are derived. These bodies 
differ very much from each other in their chemical proper- 
ties, and consequently cannot be considered as a natural 
group. The oils of spirea, bitter almonds and cinnamon, 
have been shown to be hydrurets of compound radicals. We 
may for convenience divide these products into two classes ; 
1st, those which are compounds of carbon and hydrogen ; 
and 2d, those which contain oxygen. 

§ 893. Oils consisting of Carbon and Hydrogen. — Of this 
class, oil of turpentine is the most important. It is obtained 
by distillation from the crude turpentine which exudes from 
various species of Pinus. It is a colorless liquid, of a pecu- 
liar taste and odor, has a specific gravity of -865, and 
boils at 312°. It is of great use in the arts for the prepara- 
tion of varnishes, and when carefully purified is extensively 
used for illumination, under the names of pine oil and earn- 
phene. Its probable formula is C2oHj g. When dry hydro- 
chloric acid gas is passed into the cooled oil, it is rapidly 
absorbed and a white crystalline compound of the oil and 

To what is the odor of wine due ? What is the nature of wax? § 891. 
What is the composition of athamantine ? How do this substance and 
spermaceti differ from the proper fats ? § 892. AVhat is the nature of 
the volatile oils ? How are they obtained ? § 893. Wliat are the proper- 
ties and uses of oil of turpentine ? What is its composition ? 



442 ORGANIC CHEMISTRY. 

acid, separates from a liquid of a similar composition. The 
solid body is C2oHi6» CIH. It is quite neutral, has a fra- 
grant odor, and was formerly known as artificial camphor. 
It is probable that the oil of turpentine is a mixture of two 
oils, one or both of which are CggHig. Oil of lemons \^ 
isomeric with oil of turpentine ; its probable formula is C^q 
Hs- With hydrochloric acid it forms compounds similar to 
those of that oil. The oils Oi juniper, copavia, and pepper are 
also isomeric with that of turpentine. 

§ 894. The second class of oils includes those of cloves, 
anise-seed, peppermint, lavender, rosemary, sassafras, and many 
others. Several of these have been shown to be derivatives 
of a compound radical, and it is probable that future re- 
searches will show that all of them have a similar consti- 
tution. These oils are often mixtures of different substan- 
ces, and several of them, when cooled, deposit crystalline 
compounds which are often identical in composition with 
the fluid oils, and may be related to them, as benzoine 
is to bitter almond oil ; others are products of oxydation. 
These have been designated by the general name of stear- 
optens or camphors, from their resemblance to common cam- 
phor, which may be taken as an example of them. 

§ 895. Camphor, C^qHsO. — This substance is obtained 
from the Laurus camphora and some other trees, by distilla- 
tion with water. Its properties are well known ; it is alight, 
volatile, and combustible solid, of a powerful and fragrant 
odor, insoluble in water, but soluble in alcohol. By the action 
of nitric acid it yields the camphoric acid, C^^Yi^O^, HO. 

§ 896. Oil of Mustard. — The seeds of black mustard (S^/za- 
pis nigra) contain a peculiar body named myronic acid, which 
exists in the seeds combined with potash, and associated 
with an albuminous matter called myrosine, much resem- 
bling the emulsine or synaptase of bitter almonds. When 
the seeds are bruised and mixed with water, these bodies 
react upon each other and generate the oil of mustard, 
which is then obtained by distillation. The action is prob- 
ably analogous to that which produces the oil of bitter al- 



Describe its compound with hydrochloric acid. What other oils 
have a similar constitution? § 894. What is the character of the second 
class of oils? What is their nature ? What is the nature of the solid 
compounds obtained from these oils ? § 895 How is camphor obtained, 
and what aie its properties? How is the oil of mustard obtained? 



RESINS. 



443 



inonds, (§ ^60.) The oil of mustard is a thin, colorless 
liquid, of a pungent taste and powerful odor. 

The late researches of Wertheim have shown that this 
oil is the derivative of a compound radical, CqH^, which 
he has called allijle, = All. The composition of oil of mus- 
tard is represented by the formula. All CyS2, or sulphocy- 
anid of ally le. When distilled v^ith potash, we obtain the 
sulphocyanid of potassium and oxyd of allyle, which is a 
colorless fluid with a strong odor of Ueks, and probably con- 
stitutes the essential oil of that plant. We can also form 
from it a sulphiiret of allyle, All S, which is identical in com- 
position and properties with the essential oil of garlic, 
{Allium sativa,) and may be obtained by distilling the bulbs of 
that plant with water. Several higher sulphurets of allyle 
may be formed, one of which constitutes the essential oil of 
assafetida. The oils of Aor6'e-rac?i.s'A, Ao;)^', and several other 
plants, appear to be sulphur compounds of allyle. 

VI. RESINS. 

^ 897. These are secreted by many plants, and are often 
the result of an oxydizing process upon essential oils. 
Many of them are acids, and form with alkalies distinct salts ; 
they are generally insoluble in water, but soluble in alcohol, 
and are often crystallizable. The common resin, or colo- 
phony, is a mixture of two isomeric bodies ; pinic acid, 
C2oHi5 02,and syJvic acid, C40H3QO4. When exposed to 
heat, these substances volatilize with decomposition, and 
give rise to a variety of compounds, including several car- 
bohydrogens. 

Copal appears to be a compound of several resins, which 
are but little known. 

Amber. — This curious product is found in the earth, asso- 
ciated with the remains of ancient forests. It is a mixture 
of a resinous body, with succinic acid and a volatile oil, 
and is probably formed from the resinous juices of some 
tree, by a process of oxydation. 

§ 898. Caoutchouc ; Gum Elastic, — This curious sub- 

§ 896. What is its nature ? How is the oxyd of allyle obtained, and 
what are its properties ? What is the composition of oil of garlic ? AVhat 
other oils of this group are mentioned? § 897. What is the origin of res- 
ins, and what their nature ? Give the composiiion of the acids from com- 
mon resin. What is said of amber? 



444 ORGANIC CHEMISTRY. 

Stance is found in the juices of several plants, but is princj- 
pally furnished by the Hevea guianensis and latropha elastica. 
Its ordinary properties are well known ; it is insoluble in 
water and alcohol, but soluble in ether and volatile oils. 
When softened by these solvents, it is wrought into a great 
variety of curious and useful articles."* It is very combus- 
tible, and burns with a bright smoky flame. Caoutchouc is 
composed of carbon and hydrogen. When exjx)sed to heat, 
it is decomposed, and yields a number of liquids, which may 
be separated by their difference in volatility. Some of these 
contain carbon and hydrogen in the same proportions as in 
oil of turpentine, and one is isomeric with olefiant gas. 
The mixed fluids have been largely employed as a solvent 
for gum elastic. 

VII. COLORING MATTERS. 

§ 899. A large number of organic substances have been 
grouped together under this title, because they are employed 
in coloring fabrics. This unphilosophical mode of classi- 
fication brings together bodies which are very different in 
composition and properties. A more perfect knowledge of 
them than we now possess is, however, necessary to a prop- 
er arrangement of these substances. We will notice only a 
few of the most interesting and important. 

§ 898. What are the characters of gum elastic? What is its compo- 
sition? What products does it afford by heat? § 899. What is said of 
coloring matters ? 

* Small tubes of gum elastic are very useful in the laboratory, to join 
glass tubes, and form flexible joints, (§ 380, Fig.) They are easily made 

from sheet caoutchouc in the follow- 
ing manner. A piece of the gum 
elastic is wrapped around a tube or 
rod of the required size, and then 
being held by the fingers of one hand, 
the edges are cut ofi close to the 
tube, by a pair of scissors. The 
manner of performing this will be 
seen from the figure. We now bring 
together the cut edges by a gentle 
pressure with the finger-nails, when they immediately unite firmly and 
perfectly. The tube may now be slipped off, and when applied, needs 
only to be secured by a thread Care must be taken that the scissors are 
perfectly clean, and that the fingers do not touch the freshly cut surfaces, 
otherwise they will not adhere. 




COLORING MATTERS. 445 

^ 900. The yellow coloring matters of plants are generally 
noii-azotized substances. Amonof the most imnortant, are 
quercitrine, the coloring principle of the Quercus tinctorial 
and luteoline, from the woad, Reseda lateola, both of which 
are soluble and crystalline. The yellows of turmeric and 
gamboge are of a resinous nature. Others employed in dye- 
ing are Morine, from the Morus tinctoria, and anndtto, 

<^ 901. The red coloring matters of alkanet and carthamus 
are insoluble in water, but dissolve in alkalies and are pre- 
cipitated by acids ; they appear to possess acid properties. 
The latter, carthamine, is the color of the pink saucers so 
much used in dyeing. The coloring principle of madder is 
called alizarine: it is volatile and forms orange-red crystals, 
Hematoxyline is obtained from logwood ; it is very soluble 
and forms yellow crystals ; its solution is reddened by acids, 
and rendered blue by alkalies. It gives a violet color with 
alum, and a black with persalts of iron ; for this reason it 
is much used in dyeing. 

Carmine. — This substance is extracted from the insect 
called cochineal. When pure, it is a dark red crystalline 
powder, and contains nitrogen. The pigment known as 
carmine, is a compound of this principle with alumina. 

^ 902. The green color of the leaves of plants is due to 
a substance called chlorophyle ; it somewhat resembles wax, 
and is soluble in alcohol, but insoluble in water. The blue 
color of flowers is very perishable, and has not been accu- 
rately examined. 

§ 903. Coloring Matters derived from the Lichens. — A num- 
ber of plants of this class furnish beautiful blue and red color- 
ing substances which are used in dyeing, under the names of 
archil, cudbear, and litmus. These are derived from certain 
colorless principles contained in the plants. Their nature 
may be understood from a description of one or two of these 
bodies. 

^ 904. Lecanorine is contained in a number of lichens ; it 
is a white crystalline body, which when boiled with water 



§ 900. What are the principal yellow coloring matters ? § 901. What is 
the character of the coloring matter of carthamus? Describe alizarine 
and hematoxyline. From what is carmine derived, and what are its prop- 
erties ? § 902. To what is the greeu color of plants due? § 90.S. What 
is the source of the coloring principle of the lichens? § 904. Describe 
lecanorine. How is orceiue obtained from it ? How is orcine converted 
into orceine? 

38 



446 ORGANIC CHEMISTRY. 

evolves carbonic acid, and is transformed into orcine. This 
forms large colorless crystals which are volatile, have a 
sweet taste, and are very soluble in water ; its formula is 
CieH804. When mixed with ammonia and exposed to the 
air, it absorbs oxygen and changes to orceine, which has a 
rich crimson red color. Its formula is Ci6H9N07+2HO, 
and it is derived from orcine by the addition of 1 equivalent 
of ammonia and 5 equivalents of oxygen. 

§ 905. Many other lichens contain substances which are 
very similar to lecanorine, and like it, produce fine red 
compounds. The bruised plants are mixed with water, lime, 
and an ammoniacal salt, when they undergo a kind of fer- 
mentation, and generate the red substances. These col- 
ors are rendered blue by alkalies, but acids immediately re- 
store the color. Paper stained with an infusion of litmus 
constitutes a delicate test for acids, and if reddened by a 
weak acid, it is equally sensitive for alkalies. 

INDIGO. 

§ 906. This important coloring substance is obtained from 
a large number of plants, among which the most important 
are the Indigo/era tinctoria, and /. anil, and some species of 
the genus Isatis. The plants do not contain the indigo ready 
formed, but are made to undergo a kind of fermentation with 
water ; the indigo is thus obtained in a soluble form, and 
is afterwards precipitated by agitation in contact with the 
air. The theory of this process is not well understood, nor 
do we know the state in which indigo exists in the plant. 
It occurs in commerce in masses of a deep blue color, which, 
when rubbed, assume a coppery hue and almost metallic 
lustre. This is quite impure, and does not generally contain 
more than 50 per cent, of pure indigo. It is insoluble in 
water, alcohol, dilute sulphuric, or hydrochloric acids and 
alkalies ; when exposed to heat, it is volatilized in a purple 
vapor, and condenses in crystals, which are pure indigo. 
Its composition is CigHgNOa. 

^ 907. By the action of deoxydizing agents it loses its color, 
and becomes soluble in an alkali. The ordinary process for 

What is the composition of orceine ? § 905. How are the colors pre- 
pared from the lichens? What is said of the color of litmus? §906. 
From what plant is indigo obtained? Describe the process. Give its 
composition and properties. § 907. How is indigo rendered soluble? 



INDIGO. 447 

this is to mix 1 part of indigo in fine powder with 3 parts 
of protosiilphate of iron, 4 of quicklime and a large quantity 
of water. The protoxyd of iron, which is formed, reduces 
the indigo to the colorless state, and it is then dissolved by 
the lime, forming a pale yellow solution. If this is exposed 
to the air, oxygen is absorbed, and the indigo regains its 
original color and insolubility. It is by impregnating cloth 
with this solution and precipitating the indigo in the texture, 
that the fine indigo blues are produced. 

§ 908. When we add dilute hydrochloric acid to this so- 
lution, the indigo is precipitated as a gray crystalline pow- 
der, which readily becomes blue by absorbing oxygen. The 
composition of this substance i#CigHgN02 ; it differs from 
blue indigo in containing 1 eqijivalent more of hydrogen. If 
we suppose the existence of a compound which is CjqH^ 
N = An; white indigo will be AnO, HO, and blue indigo 
An02. This view is rendered probable by many analogies. 
In the reduction of indigo then, the protoxyd formed by the 
reducing agency of the oxyd of iron, combines with 1 
equivalent of water to form the white crystalline substance. 

§ 909. Concentrated sulphuric acid dissolves indigo, and 
produces a deep blue s(^ution which contains two new acids, 
the most important of these is the sulpldndigotic acid. 
The nature of these compounds is not exactly known, but 
they are probably formed from the elements of blue indigo 
and sulphuric acid, by the abstraction of 1 equivalent of 
water. When the blue solution of sulphindigotic acid is 
boiled with woolen cloth, it is completely deprived of its 
color, the acid being taken up by the cloth. In this way the 
color known as Saxon blue is obtained. It resists completely 
the action of water, but is easily dissolved out by carbon- 
ate of ammonia, which distinguishes it from the blue colors 
obtained by the process before described. 

^910. When indigo in powder is heated with dilute nitric- 
acid, or a solution of chromic acid, it dissolves and forms 
a yellow solution, which yields, by evaporation, orange-red 

What substances are generally used for the process? Hov^^ is cloth 
dyed with hidigo? § 908. How is white indigo obtained? What is its 
composition? How does it differ from bhie indigo? How may these 
two compounds be regarded? § 909. What is the action of strong sul- 
phuric acid on indigo? How is the color called Saxon blue obtained? 
How does this differ from the blue of pure indigo ? § 910. What is the 
action of oxydizing agents upon indigo ? 



448 ORGANIC CHEMISTRY. 

crystals of a new body, called isatine. This forms beauti- 
ful rhombic prisms which are sparingly soluble in cold water, 
but readily in hot water and alcohol Its formula is CjgHs 
NO4 ; it is formed from indigo by the addition of 2 
equivalents of oxygen. When mixed with a solution of 
potash, it combines with the elements of 1 equivalent of 
water, and forms isatinic acid. If dissolved in an excess 
of a strong solution of potash and distilled, it undergoes 
a very remarkable change. Hydrogen gas is evolved with 
a peculiar oily fluid, while carbonate of potash remains. 
Ci*6H5N04 + 4(KO,HO) = Ci2H7N + 4(KO, C02)+2H. 
The new compound, 022^^7 N» which is called aniline^ is 
also formed when indigo is^istilled with caustic potash ; it 
will be described among the organic bases. 

§ 911. When chlorine acts upon isatine, it replaces 1 or 
2 equivalents of its hydrogen, and forms Mor isatine and 
dichlorisatine, C16H4CINO4 and C16H3CI2NO4. These 
bodies are isomorphous with isatine, and resemble it closely 
in color and other properties. The action of bromine is 
similar. With a solution of potash, they form acids anal- 
ogous to isatinic acid, and when distilled with excess of 
that alkali, yield organic bases simijjr to aniline, in which 
chlorine or bromine replaces 1 and 2 equivalents of hydro- 
gen. The chlorine compound named chlor aniline, C12H6 
CI N, forms beautiful crystals. 

^912. By the action of sulphuret of ammonium on isa- 
tine, we obtain a new body, isatyde, which is isatine plus 1 
equivalent of hydrogen. When sulphureted hydrogen acts 
upon a solution of isatine, sulphesatyde is formed, which is 
isatyde, in which sulphur replaces 2 equivalents of oxygen, 
C](;H6N02S2. A strong solution of potash removes the 
sulphur, and we obtain a beautiful rose- colored crystalline 
substance, named indine. This isCieNgN02, and is isomeric 
with white indigo. The metamorphoses of indigo have 
been carefully studied and a great number of curious com- 
pounds have been described. 

^913. By the long-continued action of weak nitric acid 
on indigo, we obtain the a^iilic acid, which is identical with 

Describe isatine. How is it formed from indigo ? How does it act 
with alkalies ? How is anilene formed from isatine ? Explain the re- 
action. § 91 1. How does chlorine act upon isatine ? Describe the decom- 
position of these by alkalies. §912. How does sulphuret of ammonium 
act upon isatine ? What is the composition of sulphesatyde ? What is 
the composition of indine? §913. With what is anilic acid identical? 



ORGANIC BASES, OR ALKALOIDS. 



449 



nitrosalicylic acid, (^ 778.) It is very sparingly soluble in 
water, and forms well-defined salts. When strong nitric acid 
acts upon indigo with the aid of heat, we obtain the nitro- 
picric, or carbazotic acid. This curious compound is formed 
by the action of strong nitric acid upon a number of other 
substances, among which are salicylic and nitrosalicylic 
acids, aniline and salicine. It forms yellowish white scales 
which are soluble in hot water, and have an intensely bitter 
taste. Its salts have a yellow color and explode when 
heated. The composition of the acid is 0^2 H2N3O13, HO. 
§ 914. The final action of chlorine on isatme, or any of 
the compounds mentioned above as yielding picric acid, 
gives origin to a curious volatile body, which crystallizes in 
beautiful golden yellow scales. It is called chloranile, and 
Ci^Cl^O^- 

VIII. ORGANIC BASES, OR ALKALOIDS. 

^915. These names are employed to designate a class of 
organic bodies containing nitrogen, which, like the basic 
metallic oxyds, form salts with acids. These bodies, like 
ammonia, unite directly with the hydracids, but when they 
combine with anhydrous oxygen acids, take I equivalent of 
water to form dry salts. As they generally contain 1 equiv- 
alent of nitrogen, it has been proposed to consider them 
like oxyd of ammonium, compounds of ammidogen, and 
to attribute their basic powers to the presence of that radi- 
cal. There are, however, objections to this view; we 
have no proof that oxyd of ammonium, or the ammoniacal 
salts, contain ammidogen, and there are good reasons for sup- 
posing that nitrogen, as such, enters into the constitution of 
the ammonium compounds. This same view extends to the 
alkaloids, and it is probable that it is the peculiar combina- 
tion of nitrogen itself with the other elements, which gives 
to them their basic properties. 

§ 916. The ammidids produced by the action of ammonia 
on various organic matters, have (with but a few apparent ex- 



Give its composition. How is nitropicric acid obtained ? Describe its 
properties. From what other bodies may it be formed? § 914. How is 
chloranile obtained ? Give its composition and properties. §915. What 
is meant by organic bases? How do they resemble ammonia? What is 
their probable composition? § 916. How do they difter from the com- 
pounds of ammidogen ? 

38* 



450 ORGANIC CHEMISTRY. 

ceptioiis) none of the properties of organic bases, but are 
decomposed by acids with the formation of an ammoniacal 
salt and the regeneration of the organic body. The late ex- 
periments of Fownes have shown that some of these, when 
boiled with a dilute solution of potash, are converted into 
new substances having the same composition, and even the 
same equivalent as the ammidids themselves. These have 
no longer any of the properties of the original compounds, 
and when treated with acids, combine directly with them and 
neutralize them. They are in fact converted into organic 
bases. From their characters we must conclude that these 
bodies differ from the original compounds, in the arrange- 
ment of their elements, and that they no longer contain ni- 
trogen in the condition of ammidogen. It is also worthy 
of notice that several alkaloids contain two or more equiv- 
alents of nitrogen, and yet neutralize but! equivalent of an 
acid. 

§ 917. A large number of the alkaloids are the products 
of vegetable life : they have generally active medicinal 
powers, and give to the plants their peculiar properties. 
The artificial formation of some these compounds has al- 
ready been mentioned. They are produced by a great va- 
riety of processes, as the decomposition of organic mat- 
ters by heat alone, or in the presence of alkalies, (^ 910;) 
the action of ammonia on various organic compounds, 
the transformation of certain ammidids by the action of al- 
kaline solutions and various other reactions. None of these 
are identical with any that have been found in plants, yet many 
of them have a close affinity to those produced in nature. 
Several curious bases have been formed which contain, in 
addition to the ordinary elements of such compounds, pla- 
tinum and arsenic. 

§ 918. These bodies have generally well characterized 
basic powers ; they neutralize acids, forming with them 
definite crystalline salts, and sometimes decompose salts 
of iron and other metals, precipitating their oxyds. Their 
compounds with hydrochloric acid form with chlorid of pla- 
tinum, double salts, analogous to the chlorid of platinum and 
ammonium. 

What results have been obtained by Fownes? § 917. Are the alka- 
loids natural or artificial compounds? By vi^hat processes are they 
formed? §918. What is said of their basic powers? What of their 
double chlorids ? 



ORGANIC BASES, OR ALKALOIDS. 451 

We shall notice a few of the principal alkaloids, and give 
their characteristic properties. 

§ 919. Anilene, C12H7N. — The production of this base 
has already been described ; it is also found in the products 
from the distillation of coal. It is an oily fluid which has a 
specific gravity of r028, and boils at 358°. It has an agreea- 
ble odor, a pungent taste, and is very poisonous. When 
mixed with a solution of bleaching powder, a deep blue 
color is produced, which enables us to detect the smallest 
trace of anilene. With the acids it forms salts which crys- 
tallize beautifully. It unites with cyanic acid, and forms a 
compound which is not cyanate of anilene, but a substance 
bearing the same relation to it, as urea does to the cyanate of 
ammonia ; it is in fact urea, in which anilene takes the 
place of ammonia. 

§920. Conine^ CigHigN. — This alkaloid is obtained 
from the Conium maculatu7n, by distilling an infusion of the 
plant with a solution of potash ; the salts of conine are de- 
composed, and the alkaloid distills over. It is an oily liquid 
which boils at 338° ; it has a disagreeable taste and odor, 
is a strong base, and possesses the medicinal powers of the 
€onium in a high degree. 

Nicotine, CioHgN. — This is the active principle of to- 
bacco, and is obtained by a process similar to that described 
under conine. Like the preceding bodies it is an oily liquid 
heavier than water. It has a faint odor of tobacco, with a 
burning taste, and is highly poisonous. Its alkaline proper- 
ties are strongily marked. 

Quinolcine, CigHgN. — This is an artificial base formed 
when quinine or strychnine are heated with potash, and is 
probably identical with leukol which accompanies anilene 
in coal-tar. Like the preceding alkaloids, it is liquid, vol- 
atile and poisonous. These bodies closely resemble each 
other in their sensible properties, and are analogous in com- 
position, having no oxygen and 1 equivalent of nitrogen. 

§ 921. Quinine, 020^12^02. — This valuable substance 
is one of the active principles of cinchona bark. The pro- 
cess by which it is obtained is this ; the bark is digested 

§ 919. Describe the properties of anilene? How is it distinguished? 
How does it react with cyanic acid? § 920. From what is conine ob- 
tained? What are its characters? How is nicotine produced? Give 
its composition and properties. Describe quinoleine. How do these bodies 
resemble each other ? § 921. From what, and how, is quinine obtained? 



452 ORGANIC CHEMISTRY. 

with a dilute acid, and an excess of milk of lime is added 
to the infusion, which precipitates the alkaloid mixed with 
another base called cinchonine. Hot alcohol dissolves the 
bases, and on cooling deposits cinchonine, while quinine re- 
mains in solution, and is obtained, by evaporation, in crystals. 
It is sparingly soluble in water, but dissolves readily in di- 
lute acids, forming salts which are exceedingly bitter, and 
are much used in medicine as a febrifuge. Cinchonine 
closely resembles quinine in its properties ; its formula is 
^2 0^12^0, which differs from that of quinine only in 1 
equivalent of oxygen. Like quinine it yields quinoleine 
when heated with caustic potash, hydrogen gas being evolv- 
ed and carbonate of potash formed. 

§922. Morphine, G35H20NO6. — This important alkaloid 
is a product of the Papaver somniferum, and is the active 
principle of opium, which is the inspissated juice of the cap- 
sules of that plant. It is best obtained by mixing a solution 
of opium with one of chlorid of calcium ; by filtering and 
evaporating the solution we obtain a sparingly soluble hy- 
drochlorate of morphine, which is purified by repeated crys- 
tallization. From a solution of this salt, ammonia precipi- 
tates the alkaloid ; it forms brilliant colorless crystals, 
which are insoluble in water, but soluble in alcohol. Its 
salts are crystallizable, very bitter, and possess in a high de- 
gree the anodyne properties of opium. Some of them, as 
the sulphate and hydro chlorate, are extensively used in me- 
dicine, being much more certain in their action than opium 
itself. The best opium contains 6 or 8 per cent of the al- 
kaloid. 

§923. Codeine, C35H20NO5. — This base occurs in a 
small quantity with morphine, and is a strong base ; it pos- 
sesses anodyne properties. 

Narcotine, C^qYI^s^^ia- — This is also found in consid- 
erable quantities in opium ; it is a feeble base, and its salts 
are but little known. By the action of oxydizing bodies, it 
yields a series of new and curious products, and among 
them a new organic base, cotarnine. Besides those already 
mentioned, opium affords several other alkaloids of little 
importance. 

What are its properties and uses? How is cinchonine separated from 
quinine? How does its composition differ from quinine? §922. From 
what is morpliine obtained? Describe the process. What are its char- 
acters? What use is madeof its salts? §923. Describe codeine. De- 
scribe narcotiue. 



ORGANIC BASES, OR ALKALOIDS. 553 

Strychnine, C44H23N2O8. — This alkaloid is found in the 
seeds of the Strychnos nux-vomica, and in several other plants 
of the same genus. It is prepared by a process similar to 
that described for quinine, and forms brilliant white crystals 
which are very little soluble in water, but more readily in 
alcohol. Its salts are more soluble, intensely bitter, and ex- 
ceedingly poisonous. Strychnine produces a spasmodic af- 
fection of the muscles of respiration and voluntary motion, 
and is used with great benefit in cases of paralysis. The 
dose is from |th to ^^th of a grain. The poison of the 
celebrated upas is the product of Strychnos ticute, and owes 
its activity to strychnine. 

Bruci?ie occurs with strychnine and resembles it, but is 
less powerful in its action on the animal system. 

^ 924. Solanine from the Solanum nigrum, and several 
other species ; Hyoscy amine, from Hyoscyamus niger ; Atro- 
pine, from Atropa belladonna, and Daturine, from Datura 
stramonium, are alkaline principles which possess in per- 
fection the poisonous properties of the plants from which 
they are derived. They are obtained by somewhat compli- 
cated processes, and are crystalline and volatile. Their 
salts are employed in medicine. 

^ 925. Veratrine is found in the Yeratrum album and some 
other species of the same genus ; it forms a white crystal- 
line powder, which is insoluble in water, but soluble in al- 
cohol. It is a powerful acrid poison, but is used medicinally 
in neuralgia, with beneficial results. It is applied externally 
in an ointment. > Aconiiine is obtained from the Aconitum na- 
pellus. It resembles veratrine in its properties. Sanguina- 
rine is an alkaloid which exists in the blood-root, Sanguin- 
aria canadensis^ and to which this plant owes its active 
properties. Emetine, the emetic principle of ipecachuana, and 
capsicine, to which the pungency of cayenne pepper is due, 
are also alkaloids. 

^ 926. Caffeine, Theine, C8H5N2O2. — This interesting 
compound is found in coffee, tea, the Guarana, and a species 
of Ileoc, which affords the matte, or Paraguay tea. Fine 
green tea is the best source of it, as it contains 5 or 6 per 

From what and how is strychnine obtained'? Describe its propel ties. 
What is its effect on the system and what use is made of it? What is 
the natm'e of tlie upas poison ? § 924. Describe solanine, atropine, ifcc. 
§ 925. From what is veratrine obtained? What is its use? What other 
alkaloids are mentioned? § 926. From what plants is catFeine obtained ? 



454 ORGANIC CHEMISTRY. 

cent. A strong decoction of the leaves is mixed with basic 
acetate of lead, as long as a precipitate is formed ; to the 
clear solution a little ammonia is added to precipitate the ex- 
cess of lead, and the liquid by evaporation furnishes caffe- 
ine in delicate silky crystals. It is fusible and volatile, 
sparingly soluble in cold water, but readily so in alcohol and 
ether ; its taste is slightly bitter. It forms crystalline com- 
pounds v/ith acids, but its basic powers are feeble. 

^ 927. It is worthy of notice that each of the plants that 
furnish this principle, is used by different nations to prepare 
a grateful and gently stimulating beverage. As these dif- 
erent substances resemble each other only in containing 
caffeine, it is probable that they owe their common property 
to the presence of this principle, and that in some unknown 
manner it promotes nutrition and the other vital functions. 

§ 928. The seeds of the cocoa, Theohroma cacao, contain 
a substance closely resembling caffeine. It is called theo- 
bromine and has the formula, CgH5N3 02. A great number 
of alkaline principles have been extracted from different 
plants, and besides these, many other substances which are 
destitute of basic properties, and probably somewhat anal- 
ogous to salicine and phloridzine. 

IX. STARCH AND ALLIED SUBSTANCES. 

§ 929. Under this title will be considered a class of neu- 
tral bodies of vegetable origin, which contain no nitro- 
gen, are colorless, tasteless, and possess no strongly defined 
chemical characters. Of these, the most important are 
starch, gum, pectine, and lignine. 

§ 930. Starch, Cj2HjyOjQ. — This substance exists in a 
great variety of vegetables. It is found in all the cereal 
grains, in the roots and tubers of many plants, as the potatoe, 
and in the bark and pith of various trees. It is obtained by 
bruising wheat and washing it with cold water, v/hich holds 
the starch in suspension, and deposits it on standing. Pota- 
toes furnish a large portion of starch by a similar process. 
The substances known as arrow-root, salep, sago and tapio- 

How is it obtained ? What are its properties? § 927. What is said of 
the plants which afford it? § 928. Describe theobromine. What is said 
of some other vegetable principles? § 929. What are the characters of 
the bodies of this group? § 930. From what sources is starch obtained 
and by what process ? 



STARCH AND ALLIED SUBSTANCES. 



455 




ca, are varieties of starch, obtained from different plants, 
and sometimes altered by the heat 
employed in drying. 

^931. Starch is the first organized 
body (note p. 361) that we have de- 
scribed ; when examined by the na- 
ked eye it is a white shining powder, 
but under the microscope is seen to 
consist of irregular grains, which have 
a rounded outline and are composed of 
concentric layers, covered with an ex- 
ternal membrane. The diameter of 
the grains of potatoe starch is about 
"2^ of an inch. 

Starch is insoluble in cold water, but if the mixture is 
heated, the globules swell, burst their envelops and form a 
transparent jelly, which is characterized by producing a deep- 
blue color, with a solution of iodine. 

^ 932. When starch is heated with water and a little acid 
or an infusion of malt, the mixture becomes very fluid, and the 
starch is converted into dextrine.^ This substance has a close 
resemblance to gum in its properties, and is not colored blue 
by iodine. Its composition is the same as that of starch. 
When starch is heated to a temperature of 300° or 400° it 
is rendered soluble in water, and has all the properties of 
dextrine. In this state it is used in the arts as a substitute 
for gum, under the name of British Gum or leiocome. If 
dextrine is boiled for some time with a dilute acid, it is com- 
pletely converted into grape-sugar, (^ 828.) 

^ 933. The action of malt is peculiar ; this substance is 
prepared from barley, by moistening the grain with water, 
and exposing it to a gentle heat till germination takes place, 
when it is dried in an oven at such a temperature as to de- 
stroy its vitality. The grain now contains starch-sugar and 



§ 931. What is said of the stracture of starch? What is the action of 
water? Give the composition of starch. § 932. How is dextrine formed ? 
What are its properties and composition '? From what is it named ? What 
is leiocome ? How is dextrine affected by boiling with acids ? ^ 933. 
What is malt? What is diastase and from whence its name ? 



* So named, because when a beam of polarized light is passed through 
the solution, it causes the plane of polarization to deviate to the right 
hand. 



45Q|^ ORGANIC CHEMISTRY. 

a small quantity of a substance called diastase."^ When 
a little diastase is added to a mixture of starch and water, 
at a temperature of from 130° to 140°, the starch is soon 
converted into dextrine, and in a few hours into grape 
sugar. The action of an infusion of malt is due solely to 
the presence of a minute portion of this substance, 1 part of 
which will convert 2000 parts of starch into sugar. This curi- 
ous power appears to be due to a peculiar state of the diastase, 
which is a portion of the azotized matter of the grain in a 
modified form. It is somewhat analogous to the decomposi- 
tion of amygdahne by synaptase, (§ 769) and like that body, 
diastase is rendered insoluble and inert by a heat of 212°. As 
the composition of these bodies is uncertain, this analogy 
must be only conjectural, but it will help us to understand 
the nature of this change. 

Inuline is a substance resembling starch, obtained from 
the roots of the dahlia and elecamjjane ; it yields sugar by 
the action of dilute acids. 

§ 934. Gum. — This term is applied to a number of sub- 
stances obtained from plants ; they are tasteless and very 
soluble in water, forming a liquid which is viscid and mucil- 
aginous, and from which alcohol precipitates the gum un- 
changed. Gum arable or arahine is the best example of this 
substance ; the mucilage of linseed and various other plants 
is identical with it. These bodies are metameric with dry 
cane sugar, having the formula C12H11O11, and like it are 
converted into grape sugar, by boiling with dilute sulphuric 
acid. The conversion of sugar into gum has been already 
noticed ; (^ 837) the product has the same composition as 
arabine. With nitric acid, gum yields the mucic acid, by 
which it is distinguished from starch, and all the sugars ex- 
cept lactine. 

§ 935. Pectine. — This name is applied to a principle which 
exists in the juice of many fruits, and is precipitated by alco- 
hol in the form of a jelly. In contact with alkalies it 

^ How does a solution of it affect starch ? How is this action explained? 
What is inuline ? § 934. What are the characters of gum ? With what 
body is it metameric? How is gum formed from sugar? How do dilute 
acids affect gum ? What is the action of nitric acid? § 935. What are 
the characters of pectine ? ' 

* From the Greek diistemi, to separate, because it separates the inso- 
luble envelops of the globules. 



STARCH AND ALLIED SUBSTANCES. 



457 



becomes pectic acid, which has the same property of coagu- 
lating by alcohol or acids ; sugar produces a similar effect, 
and the formation of jellies from the juices of the apple and 
currant, depends on the presence of pectine. Its probable 
formula is Ci2H80io» 

§ 936. Woody Fibre. — This substance is the solid insolu- 
ble portion of vegetables, and remains when water, alcohol, 
ether, dilute acids and alkalies have extracted from wood all 
its soluble portions. As thus obtained, it consists of two 
bodies, cellulose^ which constitutes the proper tissue, and lig- 
nine, which occurs as a deposit in the cellular substance. 
Cellulose is isomeric with starch, and is readily soluble in 
strong sulphuric acid, which converts it into dextrine. Lig- 
nine is said to contain C35H24O20 ; by strong sulphuric 
acid it is changed into dextrine, and a peculiar acid, the ligno- 
sulphuric. This experiment is best observed with cotton 
rags or unsized paper, which consist of nearly pure woody 
fibre. To two parts of this, one part of the acid is 
very slowly added, taking care to prevent any elevation of 
temperature, which would char the mixture. In a few hours 
the whole is converted into a soft mass, which is principally 
dextrine. If we dilute the mixture with water, and boil it 
for 3 or 4 hours, the dextrine is completely converted into 
grape sugar. 

§ 937. The mutual convertibility of these different sub- 
stances is interesting in relation to many of the phenomena 
of vegetable life The starch in the germinating seed is 
changed by the action of diastase into sugar, in which so- 
luble form, it seems better fitted for the nourishment of the 
embryo plant. In the growth of this, we have an example 
of the formation of cellulose from sugar, in which this sub- 
stance assumes a structural form under the action of the vi- 
tal force. This is a transformation from the unorganized to 
the organized, which mere chemical affinity can never ef- 
fect. 

§ 938. Many unripe fruits, as the apple, contain a large 
quantity of starch but no sugar. After the fruit is fully 



In vi^hat is it contained ? What is its composition ? § 936. What is v^^oody 
fibre? Of what is it made up? What is the composition of celUilose ? 
What is the action of sulphuric acid upon it ? What is the composition 
of lignine? How is dextrine prepared from cotton or other woody fibre? 
How may we convert this into sugar? § 937, What changes take place 
in the vegetation of seeds? On what do these depend ? 

39 



458 ORGANIC CHEMISTRY. 

grown, the starch gradually disappears, and in its place we find 
grape sugar. This change constitutes the ripening of fruits, 
and as is well known, will take place after they are gather- 
ed. In this process we have clearly a conversion of the 
starch into sugar, by the agency of the vegetable acids pres- 
ent in the fruit, a change which is the reverse of the previ- 
ous one, and is probably independent of life. 

TRANSFORMATIONS OF WOODY FIBRE. 

§ 939. By the action of atmospheric air and moisture, wood 
undergoes a slow decay, dependent on the absorption of oxy- 
gen, to which Liebig has applied the term eremacausis.* 
The carbon is converted into carbonic acid, while the oxy- 
gen and hydrogen of the lignine unite to form water. The 
residue is still found to contain oxygen and hydrogen in the 
original proportions, but the relative amount of carbon is con- 
tinually increasing. Thus if woody fibre contains C36H22 
022» we shall obtain first C35H2oC)2o^ ^"d then C34O18 
Hi8» 2 equivalents of water being evolved for 1 of car- 
bonic acid. The final result of this is a brown or black 
residue, which constitutes vegetable mould. Different pro- 
ducts of this decomposition have been described under the 
names of humus, geine, ulmine, humic and ulmic acids. 

^ 940. Nearly all of these bodies contain ammonia, for 
which they have a strong affinity ; this is in part absorbed 
from the air, but the late experiments of Mulder have shown 
that they have the power of forming ammonia from the 
nitrogen of the atmosphere. Pure humic acid moistened 
and placed in a close vessel filled with air, is found after 
some months to contain a considerable quantity of ammonia. 
The hydrogen evolved by a slow decomposition of the w^ater, 
is brought into contact with nitrogen under such conditions, 
that they combine and produce the alkali. 

§ 938. In what does the ripening of fruits consist? .939. How do air 
and moisture act upon wood? By what term is this process designated ? 
What is the composition of the resulting products ? What names are ap- 
plied to these bodies? § 940. What is said of their power to absorb am- 
monia ? What do the results of Mulder show? How is the ammonia 
generated ? 

* From erema, slow, and kausis, combustion, a term by which that 
chemist denotes those changes which takes place in organic bodies from 
the gradual action of oxygen. 



DESTRUCTIVE DISTILLATION OF WOOD. 459 

§ 941. The decomposition of wood, when buried in the 
ground and excluded from the action of the air, is very dif- 
ferent. The oxygen which it contains, gradually combines 
with the carbon to form carbonic acid, and we thus obtain 
substances in which the proportion of carbon and hydrogen 
is greater than in the original fibre. The substances known 
as peat, lignite, and bituminous coal, are products of this de- 
composition. The carbon and hydrogen in coal combine in 
various ways, and often generate vast quantities of gaseous 
carburets of hydrogen, (§ 451.) Anthracite has resulted 
from the action of heat on bituminous coal, which has ex- 
pelled all the volatile ingredients, and left a residue of nearly 
pure carbon. 

Destructive Distillation of Wood. 

The principal products of the decomposition of wood by 
heat are acetic acid and pyroxylic spirit, and have been al- 
ready described, (§ 8G7 § 844.) Beside these, a quantity of 
viscid tarry matter is obtained, which contains many very 
interesting compounds, 

^ 942. Kreasote. — This substance occurs dissolved in the 
crude acetic acid from wood, and is separated and purified 
by a complicated process. It is a colorless oily fluid, which 
boils at 397°, and has a specific gravity of r037 ; it has a 
peculiar and very persistent odor resembling that of smoke, 
and a powerful burning taste. It is soluble in about 100 
parts of wate-r, and the solution possesses powerful antisep- 
tic qualities. Meat which has been soaked in it, is incapa- 
ble of putrefaction,* and acquires a delicate flavor of smoke. 
The power of wood-smoke to preserve flesh, is due to 
the presence of kreasote. It is a corrosive poison when 
taken in any quantity, but a dilute solution is used medicinal- 
ly, both internally and externally as a styptic and antiseptic. 

The pure kreasote is often applied to the nerve of a de- 

§ 941. What changes does wood undergo when sechided from the air? 
What is the nature of the result? What are some of these products? 
What gases are often evolved? How is anthracite formed and how does 
it ditFer from bituminous coal ? What are some of the results of the de- 
composition of wood? § 942. What are the characters of kreasote? 
What is said of its antiseptic power ? 

* Hence the name from the Greek, kreas, flesh, and soiOf I preserve . 



460 ORGANIC CHEMISTRY. 

cayed tooth, and in this way it relieves the most violent 
toothache ; but its use requires care, for if brought in con- 
tact with the skin, it readily disorganizes it. Its composition 
appears to be G14H8O3, but its real nature is not well un- 
derstood. It combines with the alkalies to form crystalline 
compounds. 

^ 943. Eupione* — This is found with kreasote in the oil of 
wood-tar. It is a colorless, tasteless fluid, with a fragrant odor, 
boils at 117°, and has been obtained of the specific gravity 
of -633, being the lightest liquid known. The composition 
of eupione appears to be C^H^, but as its boiling point and 
specific gravity are found to vary, it is probable that several 
isomeric bodies are confounded under this name. The dis- 
tillation of wood affords many other interesting bodies, some 
of which will be mentioned in another place. 

Products of the Bistillatioi^ of CoaL 

§ 944. The distillation of bituminous coal affords a large 
quantity of carbureted hydrogen gases (§ 4.58) which are 
used for the purposes of illumination. The liquid products 
of this process are water, holding in solution much ammonia, 
and cyanid of ammonium, formed from nitrogen contain- 
ed in the coal, and a large quantity of a substance known 
as coal-tar. This contains a great number of substances, 
some of which we shall describe. 

§945. Carbolic Acid^ Hydrate of Phenyle^ C32H5O, 
HO. This substance is found in the more volatile portions 
of coal-tar. It is an oily liquid, of a pungent smell and 
taste, very like to kreasote. Its composition in 100 parts, 
specific gravity and boiling point are nearly the same, 
and as the products of its decomposition are similar, it is 
quite possible that kreasote is carbolic acid, modified by 
some unknown substance. This substance has been al- 
ready mentioned as a product of the decomposition of sal- 
icylic acid, (§ 777.) According to a recent observation of 

What of the preservative power of vvood-sinoke? What are the uses of 
kreasote? § 943. What are the characters of eupione? What is its spe- 
cific gravity I What is said of its composition ? § 944. What are the 
gaseous products of the distillation of coal ? From whence is the am- 
monia derived? § 945. Descrihe carbolic acid. What are its relations 
to kreasote ? By what process is carbolic acid formed ? How is it found 
in nature ? What is the action of nitric acid upon it ? 

* From eu, well, pioUi fat, in allusion to its oily properties. 



PRODUCTS OF THE DISTILLATION OF COAL. 461 

Wohler, it constitutes the volatile oil of the Castoreum, which 
is an animal secretion. It combines with bases forming crys- 
tallizable salts. 

Strong nitric acid converts it into nitrophenisic acid, which 
is identical witL nitropicric acid, (§ 913,) the final product 
of its action upon salicine, anilene, and indigo. This 
shows a close relation between these bodies and carbolic 
acid. 

§ 946. We may regard this substance as the hydrated oxyd 
of a YSidical phenyle, C12H5 ; it will then be allied in com- 
position to benzoic acid. A number of compounds derived 
from the decomposition of indigo and other substances, may 
be viewed as derivatives of carbolic acid, in which chlorine or 
bromine replaces two or more equivalents of hydrogen. The 
nitrophenisic acid is formed from it, by the replacement of 
3 equivalents of hydrogen by 3 equivalents of nitrous acid. 
Thus carbolic acid is C^^li^O^llO, and nitrophenisic acid 
C12H2 3N040,HO. Many other interesting relations of 
this kind may be traced out. 

§ 947. Among the liquid products of this distillation are 
found the organic bases, kyariol and leukol, which are identi- 
cal with anilene and quinoleine, (§ 919, §920,) The exist- 
ence of anilene in connection with carbolic acid is very inter- 
esting, as it has the composition of ammidid of phenyle ; 
when carbolate of ammonia is heated, it is resolved into 
anilene and water. We can now understand its formation 
from coal-tar, in which both carbolic acid and ammonia exist. 
Benzole (§ 765) has a curious relation to these bodies ; it 
maybe a hydruret of phenyle, C12H5H. When nitroben- 
zole C12H5NO4 is treated with sulphureted hydrogen, the 
sulphur separates, and while 4 equivalents of hydrogen com- 
bine the oxygen to form water, two unite with the product 
to form anilene. Ci2H5N04 + 6Hrr:Ci2H7N + 4HO. 
Dintrobenzole, Cj 2H42NO4, by the same process affords 
a new organic base. It is called nitranilene, and is anilene 
in which NO4 replaces Hr=Ci2H4N04N, (§ 910, §911.) 

§ 948. Naphthaline, 020^3. This substance is found in 
large quantity in coal-tar, and is a frequent product of the 

§ 946. What view may we take of its composition ? How is nitrophe- 
nisic acid formed from it? § 947. What hquid bases are found in coal- 
tar? How is anilene related to carbolate of ammonia, and how may 
it be formed from it? What may we consider benzole? How does sul- 
phureted hydrogen act on nitrobenzole ? 

39* 



462 ORGANIC CHEMISTRY. 

decomposition of organic substances at a high heat. It is 
formed abundantly when camphor is passed through a tube 
heated to whiteness. It is volatile, and forms beautiful white 
crystals, of a fragrant odor and pungent aromatic taste. The 
action of chlorine, bromine, and nitrous acid on naphthaline, 
gives rise to a great number of compounds, which have late- 
ly been studied by Laurent. They are formed by successive 
substitutions of the hydrogen by one or more of these sub- 
stances, and a great number of isomeric modifications of each 
of these bodies may exist ; some of these have been men- 
tioned in illustrating the law of substitution, (^ 686.) The 
body C2oH(jCl2 occurs in 7 modifications, which are per- 
fectly distinct in their characters. We are forced to sup- 
pose that these compounds owe their different properties to 
a different arrangement of their constituent atoms, and it is 
easy to see that, in this way, the number of possible com- 
binations will be immense. More than twenty substances 
have been described, in which chlorine is in part sub- 
stituted for the hydrogen of the naphthaline. The final pro- 
duct of the action of chlorine is CsoClg, being a chlorid of 
carbon, which preserves the type of naphthaline. 

^ 949. Petroleum. — In many parts of the world, an oily 
matter exudes from the rocks, or floats on the surface of 
springs. The principal sources of this substance are Amia- 
no in Italy, Ava, and Persia, but it is found in many places 
in our own country. The Seneca Oil, well known in this 
country, is an instance of this kind. Petroleum is a varia- 
ble mixture of several bodies. By distillation, it yields a 
colorless liquid called naphtha, which is very light, volatile 
and combustible. Its formula is C6H5. Naphtha occurs 
nearly pure in Italy and Persia, and is used for illumination. 

Petroleum contains a variety of other bodies, among 
which is parajffine, a white, solid hydro-carbon which 
occurs in the products of distillation of wood and coal, and 
several resinous matters, formed perhaps by the oxydalion 
of naphtha. These substances are probably derived from 
coal or other matters of vegetable origin. 

§ 948. Give the composition and properties of naphthaline. How is it 
formed ? What is the action of chlorine, bromine, and nitrous acid upon 
it? What is said of the modifications of these compounds? How are 
these facts explained ? W^hat is the final result of the action of chlorine ? 
§ 949. What is petroleum ? How is naphtha obtained ? What are its 
composition and properties ? From what source is parafnne obtained ? 
What is the origin of petroleum ? 



NUTRITIVE SUBSTANCES CONTAINING NITROGEN. 463 



NUTRITIVE SUBSTANCES CONTAINING NITROGEN. 

§ 950. All vegetables afford, in addition to lignine, starch, 
sugar, and the other bodies before described, a peculiar class 
of compounds which contain nitrogen and a small quantity 
of sulphur. These substances are tasteless, often insoluble 
in water, and are highly nutritious. They occur to a still 
greater extent in animals, of which they constitute the mus- 
cular fibre, and are dissolved in the fluids of the body. 
These substances are very analogous in their composition 
and chemical characters. 

^951. Vegetable albumen is found in the juices of many 
plants. It closely resembles animal albumen, and like it is 
coagulated by heat. When a paste of wheat flour is washed 
with water, a large quantity of starch separates, and a very 
tenacious substance remains, which is known as gluten, 
and is principally vegetable jibrine. It forms a gray translu- 
cent mass which is soluble in acetic acid. Legumine, or 
vegetable caseine is found in the seeds of beans and peas. 
When the seeds are bruised with water, the legumine dis- 
solves ; acetic acid coagulates the solution, and precipitates 
it in a form resembling the curd of milk. 

§ 952. These substances are very prone to decomposition, 
and when exposed to air and moisture, soon undergo putre- 
faction. The remarkable power which they possess to in- 
duce change in other bodies has been frequently noticed. The 
conversion of ^ugar into lactic and buytric acids, is due to the 
action of decomposing caseine, (^ 837, ^ 889 ;) and synaptase, 
which is an analogous compound, probably owes its singular 
power (^ 769) to a similar condition. Diastase (^ 933) is a 
modified form of gluten. Yeast, which is a deposit from beer 
and other fermenting liquids, is similar to these, and iden- 
tical with the substance mentioned as producing the vinous 
fermentation, (^ 834.) 

^ 953. The process of bread-making illustrates the action 

§ 950. Describe the characters of the nitrogenous nutritive substances. 
In what are they found? § 951. Where does vegetable albumen occur, 
and what are its properties? How is vegetable fibrine obtained? De- 
scribe it. From what is legumine obtained? What docs it resemble? 
§ 952. What peculiar tendency of these substances is mentioned? Men- 
tion some elfects which are ascribed to this. What is the nature of yeast ? 
§ 953. Explain the process of bread-making ? 



464 ORGANIC CHEMISTRY. 

of this substance. The essential ingredients in flour are 
vegetable fibrine, starch, and sugar. The flour is made into 
a paste with water, yeast is added, and the mixture is put in 
a warm place. The yeast induces the vinous fermentation 
in the sugar, forming alcohol and carbonic acid gas, which, 
from the viscid nature of the paste, inflates it, and gives to 
it its peculiar lightness and porosity. The power of yeast 
and similar bodies is completely destroyed by boiling: water, 
strong alcohol, essential oils, various metallic salts, and many 
other substances, all of which are known to act as antisep- 
tics. 

§ 954. Animal Albumen. — This substance is found abun- 
dantly in the white of eggs and the serum of the blood. Al- 
bumen is soluble in water, especially with the aid of an 
alkali, but is readily precipitated from its solutions by acids. 
When exposed to a temperature of about 150'^, it is changed 
into a white mass which is no longer soluble. 

Animal Fibrine. — This substance is dissolved in the 
chyle and blood, and constitutes the muscular parts of animals. 
It is easily obtained by stirring freshly drawn bullock's 
blood ; the fibrine adheres to the stick and may afterwards 
be washed with water. It is a white fibrous mass, which 
when dry is horny and translucent. Fibrine is readily sol- 
uble by a gentle heat in solutions of sal-ammoniac, nitre, 
and several other salts. When thus dissolved, it has the 
properties of soluble albumen and is coagulated by heat. 
Both fibrine and coagulated albumen, are soluble in water, 
containing 2oVo^^ P^^^ ^^ hydrochloric acid. 

§ 955. Caserne. — This substance constitutes the curd of 
milk. When pure it is quite insoluble in water; but in 
milk it is rendered soluble by combination with a little al- 
kali. Its solution is immediately coagulated by dilute acids, 
which combine with the precipitated caseine. The spon- 
taneous coagulation of milk is due to the formation of lactic 
acid from the sugar of milk, by the agency of a portion of 
the caseine in a state of incipient decomposition, (^ 839.) 
This change goes on until the whole of the sugar is con- 



What agents destroy the power of yeast ? § 954. Where is albumen 
found? What are its properties? What are sources of fibrine? De- 
scribe the mode of obtaining it, and its properties ? By what is it dissolv- 
ed? What does it then resemble? §955. Where does caseine occur? 
What are its properties? To what is the curdling of milk due? 



NUTRITIVE SUBSTANCES CONTAINING NITROGEN. 465 

verted into lactic acid. In the manufacture of cheese, the 
process is facilitated by the addition of a little rennet. This 
substance is prepared by digesting the lining membrane of 
a calf's stomach in water, and appears to act like caseine 
by imparting to the milk its peculiar condition. 

^ 956. Proteine, — When any one of these bodies is dis- 
solved in a dilute solution of potash by a gentle heat, ace- 
tic acid precipitates from the liquid a white pulverulent 
substance, which Mulder, its discoverer, has named pro- 
teine.* The composition of this body is the same, from 
whatever source it is obtained, and leads to the formula 
^4 0^30^5^3 2- The substances from which it is de- 
rived always contain phosphate of lime, and frequently salts 
of soda. Beside this, there is invariably present a small 
portion of sulphur, and in albumen and fibrine, traces of phos- 
phorus. The quantity of sulphur is small, being on an 
average about ^-^-^th part ; it is separated in the form of sul- 
phuret of potassium when the substance is dissolved in potash, 
and can be detected by a salt of lead, which affords with 
the solution a black precipitate of sulphuret of lead. The 
proportions of oxygen, hydrogen, nitrogen, and carbon, in 
these bodies are the same as those in proteine. 

^957. We, may conceive proteine to be allied to fibrine, 
albumen, &c., in the same manner as dextrine is to starch 
and cellulose. The different condition of these several sub- 
stances may be regarded as the result of organization, for 
we have seen that fibrine may be readily converted into al- 
bumen without any change of composition. The sulphur in 
these compounds is probably due to the presence of a sul- 
phureted body not yet separated, which is decomposed by the 
potash. As its quantity is very small and the proportions of 
its organic elements quite similar to those of proteine, we 
observe no difi'erence between the analysis of proteine and 
the organic tissues. 

What is the nature of rennet? §956. How is proteine obtained? 
What is its composition, and whence its name? What substances are al- 
ways associated with it? What is the amount of the sulphur? How 
do these bodies compare in composition with proteine? §957. How 
may we suppose proteine to be related to the substance from which it is 
derived ? To what are the differences due ? To what may tlie sulphur be 
ascribed ? 

* From the Greek, proteuo, I take the preeminence, in allusion to the 
large class of substances of which it is supposed to be the basis. 



466 ORGANIC CHEMISTRY. 

§ 958. Proteine and all the bodies of this class are solu- 
ble in strong hot hydrochloric acid, and yield a purple solu- 
tion, which, by exposure to the air, absorbs oxygen and be- 
comes black. The solution now contains sal-ammoniac and 
humate of ammonia. Humic acid has been mentioned as 
a result of the decay of woody fibre, (^ 939 ;) it contains 
^40^12^12- The elements of ] equivalent of proteine, 
plus 3 of oxygen =: 1 equivalent of humate of ammonia, 
^4o^i2^i2'^K4^5 plus 4 equivalents of ammonia which 
form sal-ammoniac with the hydrochloric acid, and 2 equiv- 
alents of water. 

Mulder has described a deutoxyd and tritoxyd o^ proteine ; 
the former of these is found in the blood in inflammatory 
diseases. Both of these oxyds are formed when proteine is 
boiled in water, oxygen being absorbed from the air. 

§ 959. Gelatine. — This substance is contained in many 
tissues of the body, as the skin, cellular membranes, tendons 
and ligaments, and constitutes nearly 40 per cent, of the 
bones. It is extracted from these substances by boiling 
water, and the solution on cooling becomes a firm jelly ; 
this property is very characteristic of gelatine. It is 
found nearly pure in isinglass or fish-glue. Its solution 
forms a very insoluble precipitate with an infusion of nut- 
galls, or a solution of tannic acid. When the skin of ani- 
mals is steeped in an infusion of oak bark or of any other 
vegetable containing tannic acid, this insoluble compound 
is formed and constitutes leather* The formula of gelatine 
is CjaHj^oNoOg. The substance of cartilage has been 
named cJiondrine ; it resembles gelatine in its properties, but 
differs a little in composition ; both of these bodies, like the 
proteine compounds, contain traces of sulphur 

THE BLOOD. 

§ 960. This substance when recently taken from the 
body is a homogeneous slightly viscid liquid, but soon forms 



§ 958. What is the action of hydrochloric acid on proteine? What 
are the products of its decomposition? Explain the reaction. What is 
humic acid? What are the oxyds of proteine? §959. From what sub- 
stance is gelatine obtained? What are its characters? What is the na- 
ture of leather ? What is chondrine ? What do these bodies possess in 
common with the proteine compounds? § 960. What changes does the 
blood undergo, when taken from the body ? 



THE BLOOD. 467 

a tremulous jelly, which by standing contracts into a hard 
coagulum, floating in a yellowish liquid called the serum. 
This has a saline taste, and contains in solution alkaline 
chlorids and phosphates, with a large portion of albumen. 
It has an alkaline reaction, which is due to the presence of 
the tribasic phosphate of soda, 3NaO, PO5. 

The coagulum of the blood has a dark-red color and con- 
sists of a mass of iibrine mixed with the red globules, 
which constitute the coloring matter of the blood. If the 
fresh liquid is mixed with several volumes of a solution of 
sulphate of soda, the fibrine remains dissolved, (§ 954,) and 
the globules collect at the bottom of the liquid as a sediment. 

§ 961. The form and size of these globules vary in differ- 
ent animals ; in the blood of man they are thin discs from 
3(/QQth to eo^oo^h of an inch in diameter. They consist of 
a colorless sac, of a composition similar to fibrine, which 
encloses a soluble red matter. When placed in water, these 
corpuscles burst and form a red liquid containing albu- 
men and the coloring principle which is named hematine. 
This is readily soluble in alcohol containing a little acid or 
ammonia, by which it is separated from the albumen. The 
solution has a deep-red color even v^hen much diluted. Pure 
hematine coritains about 6 per cent, of iron, which cannot be 
separated from it by dilute acids. Its composition may be 
expressed by the formula C4 4H2 2N30(jFe. If it is mixed 
with strong sulphuric acid, and water gradually added to 
the mixture, hydrogen gas is evolved, and the hematine sep- 
arates as a dark-red mtiss, while the iron remains in so- 
huion. The hematine thus prepared is entirely free from iron ; 
but its composition is in other respects the same as before, 
being C44H22N3O6. This shows that the red color of the 
blood is not necessarily due to the presence of compounds of 
iron, as has been supposed, and that the iron does not exist 
in the blood as an oxyd. 

§ 962. The color of the arterial blood is scarlet, while 
that in the veins is a dark-red, and the solutions of hema- 
tine have the same tint. The venous blood acquires the 

What is the composition of the sernm? Of what does the coaoruhim or 
clot consist? How may these globules be separated? §961. Describe 
tne globules of human blood ? What is the action of water upon them ? 
How is the hematine obtained ? How may the iron be separated ? In 
what state does the iron exist? §962. What are the dilTerent colors of 
the blood, and by what produced ? 



468 ORGANIC CHEMISTRY. 

bright scarlet tint while in the kings, but loses it again in 
the capillary vessels. This change has been attributed to the 
absorption of oxygen by the coloring matter, but hematine un- 
dergoes no change of color by the action of the air. If we 
mix arterial blood with water, it immediately assumes a dark- 
red color, which is not altered by oxygen gas, but a solution 
of any neutral salt will restore the scarlet tint, even in a 
vacuum. A little milk or a mixture of chalk and water will 
immediately give a bright color to venous blood, or a solu- 
tion of hematine. This effect seems due to the light re- 
flected from the white particles, and the saline liquids pro- 
duce the same effect by coagulating the exterior of the glo- 
bules and rendering them white. Mulder supposes that the 
action in the lungs, consists in an oxydation of a portion of the 
fibrine of the blood, by which a white layer of oxyd of pro- 
teine is formed on the surface of the blood globules. This 
oxyd is taken up in the capillary vessels and the globules 
reacquire their dark-red tint. This view must be consid- 
ered as only an ingenious hypothesis, but it is certain that 
the difference of color is not due to any change in the he- 
matine itself. 

^ 963. In addition to the substances already mentioned, 
the blood contains globules of fatty matter. 1000 parts of 
blood afford 790 parts of water, 68 of albumen, and 10 9 
parts of salts with a little fat, which are dissolved in the 
serum. The clot contains about 1386 parts of albumen 
and fibrine, and 2-97 parts of hematine, besides 2-4 parts of 
fatty substances which contain phosphorus. The salts of 
the blood are principally alkaline chlorids and phosphates 
with phosphate of lime. The proportions of the ingredients 
often differ from these, being varied by many circumstances. 

§ 964. Chyle. — This fluid is taken up by the lacteals 
from the smaller intestines, as a white opake fluid. It con- 
tains a proteine compound in solution, and a great number of 
globules of fat to which its milky appearance is due, besides 
various salts, and a small portion of iron in a soluble form. 
When the chyle is first taken up by the lacteals, it contains 

Show that this does not depend on the action of the oxygen. How do 
milk and sah'ne fluids alter the tint of the blood? What is Mulder's 
view ? § 963. What other substances does the blood contain ? State the 
composition of the serum. Of the coagulum. What are the saline 
ingredients of the blood? § 964. What is the nature of the chyle? 
W^hat differences are observed in it ? What are its morganic ingredients ? 



GASTRIC JUICE. 469 

but little fibrine, but a large portion of albumen. But the 
chyle from the thoracic duct coagulates like the blood into 
clots which contain fibrine, while the clear fluid that sepa- 
rates, resembles the serum of the blood. Lymph, the fluid 
of the lymphatic vessels, differs from chyle principally in 
being more dilute, and in the absence of the fatty globules. 

THE GASTRIC JUICE. 

§ 965. This fluid is secreted from the coats of the stom- 
ach by the stimulus of food. It is a slightly saline fluid 
with an acid reaction, and contains chlorid of sodium, traces 
of phosphate of lime, a small quantity of dissolved animal 
matter and a free acid. This according to the experiments 
of Berard and Barreswil, is the lactic acid. The animal 
matter appears allied to the proteine compounds, and has 
been cdXlQ^L pep sine ; but is probably not a distinct substance. 
The gastric juice has a remarkable solvent power ; muscular 
fibre, coagulated albumen, and various other substances are 
completely dissolved by it. This property is not confined 
to the gastric juice while in the stomach ; when taken 
from the body it produces the same effect, if kept at the 
temperature of the system, (about 100° F.) If it is heated for 
a short time to 200° F., this solvent power is completely de- 
stroyed ; the same effect is produced by neutralizing the 
free acid, but a small portion of any acid restores its ac- 
tivity. The solvent power of the gastric juice appears then 
to be due to the conjoined influence of the acid and animal 
matter. As the activity of this last is immediately destroyed 
by boiling water, alcohol and some other antiseptic agents, 
it has been supposed to be a proteine body in a state of 
change, (§ 952,) and the process of digestion is regarded as a 
kind of fermentation, induced by this substance with the 
aid of an acid. The change, however, appears scarcely 
analogous to any phenomena of this kind, and although this 
idea is probably the nearest approximation to the truth, the 
subject is still obscure. 

§ 966. The Saliva. — This fluid contains a peculiar animal 
matter which has been called ptyaline, with a considerable 

What is the nature of lymph ? § 965. How is the g-astric fluid secre- 
ted ? What does it contain? What remarkable property has it? What 
circumstances affect this power ? To what does it a])pear to be due ? 
What view has been taken of the digestive process ? What is said of it? 

40 



470 ORGANIC CHEMISTRY. 

portion of saline matter ; this consists principally of chlo- 
rids of potassium and sodium and the tribasic phosphate of 
soda, to which the alkaline reaction of the secretion is due. 
In addition to these are found small quantities of earthy- 
phosphates and a trace of sulphocyanid of potassium. The 
saliva appears like the gastric juice to have a solvent power 
on animal substances, and seems to prepare the food for the 
process of digestion. The pancreatic fluid resembles the 
saliva in composition, but nothing definite is known as to its 
uses or properties. 

THE BILE. 

^ 967. This fluid is a secretion of the liver, and is found 
in the gall-bladder. It is viscid, has a greenish-yellow col- 
or and an alkaline reaction. Bile consists of the soda salt 
of a peculiar fatty acid, with a small portion of a crystalline 
fat called cholesterine, and a peculiar coloring matter. This 
acid is called the choleic^ and bile is a solution of choleate of 
soda. 

^ 968. The bile and the other alkaline choleates have the 
characters of soaps, and the use of this liquid in removing 
oil stains depends upon this property. Its composition is, 
however, very different from that of the oily acids before 
described, as it contains nitrogen and sulphur. The formu- 
la which has been given is C4 4H3 5N0i2» HO, but as tau- 
rine^ a product of its decomposition, has recently been found 
to contain a large amount of sulphur, this must be modified. 

The acid is slightly soluble in water, but readily in alco- 
hol. When boiled with hydrochloric acid it is decomposed 
and affords a number of new substances. 

§ 969. This fluid appears to perform an important part in 
digestion ; it mixes with the food in the duodenum, and ap- 
parently aids in the elaboration of the chyle. It is probable 
that, by its peculiar properties, it renders the fatty portions of 
the food soluble, and it is supposed by some, that it has the 
power of converting starch and sugar into fat. This, how- 
ever, requires proof. Its presence appears essential to the 

§ 966. What is the composition of the sahva? What saline substan- 
ces does it contain? § 967. What is the composition of the bile ? § 968. 
What useful property has this fluid ? What is pecuhar in its composi- 
tion? § 969, What appears to be the use of the bile? What experiment 
shows that it is important in the digestion of food ? 



THE URINE. 471 

assimilation of food ; if the duct which conveys the bile 
to the duodenum is divided, and an artificial outlet is provi- 
ded for it, the secretion is performed as before, yet the ani- 
mal becomes emaciated and dies, apparently from imperfect 
nutrition. Still, this fluid appears to be, to a great extent, an 
excretion of the system. 

THE URINE. 

§ 970. This excrementitious fluid, which is separated from 
the blood by the action of the kidneys, is a medium for the 
removal of various saline and azotized matters which are 
unfitted for the purposes of life. The organic substances 
thus discharged, are urate of ammonia, urea and hippuric 
acid. The urinary secretion of birds, reptiles, and in- 
sects, which is white and solid, is principally urate of 
ammonia. That of herbivorous animals contains urea and 
a large quantity of hippuric acid, which in the carnivora 
is entirely replaced by urea and a little uric acid. This is 
nearly the composition of that of man, subsisting on a mixed 
diet. The average proportion of urea in healthy human 
urine is about 3 per cent., but is varied by many causes. 
The amount of uric acid is about j-^-fj^ of the urine ; in ad- 
ditior^ to these, it contains a small portion of hippuric acid 
and an organic coloring matter. The saline matters gene- 
rally amount to 2 or 3 per cent., and consist of chlorid of 
sodium, sulphates and phosphates of potassa and soda, with 
traces of amnioniacal salts, and phosphates of lime and mag- 
nesia. Fresh urine has an acid reaction, which is ascribed 
to the uric acid that is held in solution by the phosphate 
of soda. Pure urine undergoes no change by keeping, but 
when in contact with the mucus of the bladder it is rapidly 
decomposed, and the urea is converted into carbonate of am- 
monia, (^ 718.) 

^ 971. In diseased states of the system the composition 
of this fluid is sometimes altered, and the uric acid 



What is said of its relation to the system? § 970. What is the office 
of the urine? What are the organic substances of urine? What is the 
character of that of birds, &c.? What of herbivorous animals and of 
man? What is the ordinary proportion of urea and uric acid in human 
urine? What are the saline matters and what is their amount? To 
what is its acid reaction due? How is it changed by keeping? § 971. 
What is the origin of calculi ? 



472 ORGANIC CHEMISTRY. 

or earthy salts, rendered less soluble or more abundantly- 
secreted, are deposited in the bladder, forming stony concre- 
tions or calculi. They are most frequently uric acid or urates, 
and the phosphates of lime and magnesia ; oxalate of lime 
frequently occurs in this form, although oxalic acid does not 
exist in healthy urine. 

THE BRAIN AND NERVOUS MATTER. 

§ 972. These substances have a close resemblance in 
their organization and chemical composition ; the white and 
gray portions of the brain differ principally in their structure. 
The brain contains about 20 per cent, of solid matter, the 
rest is water. About one third of the solid substance resem- 
bles albumen ; the remainder is composed of several fatty 
substances, some of which are quite peculiar in their com- 
position, from containing nitrogen and phosphorus ; the 
amount of this last element is about 4 per cent, of the solid 
matter. The cerehric acid is obtained in white crystalline 
grains, and forms very insoluble salts. The oleo-phosphoric 
acid is a compound of phosphoric acid with an oil resembling 
oleine, and is decomposed into these, by long boiling with 
water. The cerebral ^ubstance contains besides these, the 
crystalline fat found in the bile, cholesterine, and some jother 
substances which have not been thoroughly studied. The 
fatty matter of the blood, consists in part of cholesterine and 
a substance which contains nitrogen and phosphorus, and 
is analogous to cerebric acid. 

MILK. 

§ 973. This secretion designed for the use of the young 
animal, contains all the substances necessary for its proper 
development. The proportion of its ingredients is very va- 
riable, but the following analysis of cows' milk may be taken 
as an average: 1000 parts contain water 873; butter 30; 
caseine 48*2 ; milk sugar 439 ; phosphate of lime 2*3 ; 

Of what do they consist? § 972. What is the nature of the brain and 
nervous matter? What is the amount of the solid matter? Of what 
does it consist ? What proportion of phosphorus is found in the brain ? 
What are the fatty acids of this substance ? What is the nature of the 
fatty substances of the blood? § 973. What does milk contain? Give 
the composition of cow's milk. 



BONES. 473 

chlorids of potassium and sodium 1'68, with small quantities 
of phosphates of iron and magnesia, besides soda in combi- 
nation with caseine. These substances have been already- 
described under their separate heads. Human milk contains 
proportionably more sugar, but does not differ in other re- 
spects. That of carnivorous animals contain caseine and 
butter, but no sugar, and corresponds to their food, which 
consists of proteine compounds and fat. 

BONES. 

§ 974. Bones consist of a tissue of cartilaginous sub- 
stances enveloping a large quantity of earthy salts. Those 
of adult animals usually afford from 37 to 42 per cent, of 
organic matter, which is principally dissolved by boiling 
water and constitutes gelatine. The earthy matter, vary- 
ing from 58 to 63 per cent., is principally phosphate of lime. 
The following analyses are from Berzelius : 

Human Bones. Ox Bones. 

Animal matter dissolved by boiling, - - 3217 } qq-qh 

Insoluble vascular substance, _ _ - 1-13 ^ 

Phosphate of lime with a little fluorid of calcium, 53-04 57-35 

Carbonate of lime, 11-30 3-85 

Phosphate of, magnesia, - - - - 1 16 2.05 

Soda and chlorid of sodium, - - - - 1-20 345 

100-00 100-00 

The phosphate of lime, according to the latest researches 
of Berzelius, 'is the tribasic phosphate, 3CaO, PO5. The 
bones of infants contain comparatively less earthy matter 
than those of adults, and the same fact is observed in rickets 
and some other diseases connected with defective nutrition. 

^ 975. The teeth have a composition very similar to bones, 
but the quantity of organic matter is less. The skeletons of 
mollusca and of zoophytes, are composed of animal matter 

How does human milk differ ? What is the composition of that of the 
carnivora? How does this agree with their food? § 974. What is the 
nature of bone? What is the amount of organic matter and what its 
nature? What is the nature of the insoluble portion? Give the com- 
position of human bones. What is the composition of the phosphate of 
lime? In what cases is the amount of earthy salts diminished? § 975. 
What is the composition of the teeth? Of the skeletons of mollusca? 
Of corals ? 

40* 



474 ORGANIC CHEMISTRY. 

with carbonate of lime, and small traces of phosphates of lime 
and magnesia with fluorid of calcium.* 

XUTRITION OF PLANTS AND ANI3IALS. 

§ 976. The animal creation is entirely dependent for its 
support upon the products of the vegetable. Plants assimi- 
late inorganic matter, and give it a form which fits it for the 
support of animals. We may then properly consider first, 
the nutrition of veoretables. The ororanic substances essen- 
tial to plants are cellulose and proteine ; these enter into the 
structure of the smallest vegetable, and are necessary to the 
formation of cells, which are the first rudiments of organic 
development. Besides these, plants may contain sugar, oils, 
acids and resins, but these are not necessary to their con- 
stitution. 

^ 977. The proteine compounds contain small portions of 
sulphur and phosphorus, and the ligneous fibre is never des- 
titute of inorganic salts ; these are always found dissolved 
in the fluids of the plants, and are essential to its perfect de- 
velopment. Some of them are decomposed by the plants, 
to furnish sulphur and phosphorus for the albumen and other 
proteine bodies, but beyond this, little is known of the func- 
tions of these substances. The seeds of vegetables con- 
tain starch and proteine, which serve for the nourishment of 
the plant (§ 937) until its organs are sufficiently developed to 
enable it to support itself from external sources. 

^ 978. The food of plants consists of carbonic acid, water 
and ammonia, in addition to the mineral salts already men- 
tioned. These are absorbed by the organs of the vegetable 
and are converted into cellulose and proteine ; the power by 
which this is effected is unknown ; chemical affinity is con- 
trolled and directed by the agency of life so as to produce 
complex and highly organized bodies. We know, however, 
the substances which enter into combination, and the results 
of their action ; in this way the formation of these bodies 
maybe expressed by formulas. 

§ 976. What is the relation of the vegetable to the animal world? 
What bodies are essential to the formation of a plant? § 977. What is 
said of the inorganic salts and their decomposition ! What purpose is 
subsen'ed b}^ the starch and proteine of seeds ? § 978. What consti- 
tutes the food of plants? How are these changed? What is said of 
the power wliich effects this ? 

* Am. Jour. Science, (2d series,) March, 1846, p. 189. 



NUTRITION OF PLANTS AND ANIMALS. 475 

^ 979. The cellular tissue is formed from the elements of 
carbonic acid and water, by the separation of oxygen ; 12 
equivalents of carbonic acid with 10 equivalents of water; 

^12^2 4 + ^10010 = ^512^10^10 + 1^0 5 o^ 1 equivalent of 
cellulose and 10 of oxygen. In the formation of proteine, 
the elements of ammonia are added to those of carbonic 
acid and water. 40 equivalents of carbonic acid with 15 of 
water and 5 of ammonia=l equivalent of proteine and 83 
of oxygen. It has been shown (§ 956) that proteine, under 
certain circumstances, absorbs oxygen and is decomposed 
into ammonia and humic acid. This last is formed from 
woody fibre, by the loss of the elements of water and car- 
bonic acid ; proteine may, therefore, be produced from cel- 
lulose by adding ammonia and subtracting carbonic acid and 
water. 

^ 980. All the other principles of plants may be formed 
in a similar manner. Starch is identical in composition 
with cellulose, and yields sugar and gum by combining with 
the elements of water. Malic acid is formed from the 
elements of 8 equivalents of carbonic acid and 4 of water, 
by the abstraction of 12 equivalents of oxygen, and the other 
acids are produced by an analogous process. It is probable 
that the saline and alkaline matters in the sap, exercise som.e 
influence on these processes, and conduce to the formation of 
the various products. 

§ 981. The oxygen which is set free in all these reactions 
is evolved from the leaves in the form of gas. If a branch 
of any plant is placed under an inverted receiver, filled with 
pure water, and exposed to the sun's light, small bubbles of 
gas will appear on the leaves, which rise and collect in the 
upper part of the jar. This gas is pure oxygen, and is evol- 
ved by all healthy plants when exposed to the light ; in 
darkness, the process of nutrition is very imperfectly per- 
formed, and the carbonic acid absorbed by roots is given off 
from the leaves unchanged. If a plant is made to grow^ in 
a vessel containinoj a mixture of common air and carbonic 



§ 979. From what is cellular tissue formed ? Explain it upon the black- 
board. From what may proteine be formed? Explain it. How may it 
be formed from cellulose? § 980. Kow are starch, gum, and sugar rela- 
ted to cellulose? How may malic acid be formed? § 9S1. What is 
evolved in all these reactions? How may this be shown? What is the 
influence of light in this process ? How does a growing plant act upon 
carbonic acid ? 



476 ORGANIC CHEMISTRY. 

acid gas the latter will be slowly absorbed and repla- 
ced by pure oxygen. Plants have the power of absorb- 
ing gaseous carbonic acid and water through their leaves 
as well as by their roots ; they also exhale large quaa- 
tities of water from the pores on the surface of the leaves. 

§ 982. A soil fitted for the growth of plants must contain 
in a soluble form, all the salts and mineral constituents which 
they require. These vary in different plants ; their na- 
ture and quantity are determined by minute analyses of the 
ashes of each vegetable. The most important are potash, 
lime, magnesia, and iron, combined with sulphuric, phospho- 
ric and silicic acids, and chlorine. Plants have the power 
to decompose these salts ; we have observed that they sep- 
arate sulphur and phosphorus to form the proteine compounds, 
and all of them contain salts of potash with vegetable acids, 
' as in the grape, (§ 869.) The alkali in these has been sepa- 
rated from its combination with the mineral acids ; when the 
plant is burned, these salts are decomposed, and produce 
the carbonate of potash, which the ashes of vegetables al- 
ways contain, (§ 507.) 

§ 983. Many of the mineral substances are contained 
in the rocks, from whose disintegration the soil was form- 
ed, and their slow decomposition gradually liberates them in 
a soluble form. Often, however, by long cultivation, some 
particular ingredients of the soil become exhausted, and it 
is no longer productive. Its fertility may then be restored 
by the application of some mineral manures, as wood-ashes, 
or bone-dust. A soil which has become unfitted for the 
growth of one plant, may still contain the substances neces- 
sary to the support of another, and hence the utility of ro- 
tation in crops. The ashes of tobacco contain a large amount 
of potash, while wheat and other cereal grains abound in 
phosphate of lime ; so that a soil well adapted to the growth 
of tobacco may not be suited to wheat, and vice versa. 

§ 984. Fertile soils generally contain, in addition to these, 
a portion of humus from the decomposition of vegetable 
matter. This is beneficial by its slow decomposition, by 

How do the leaves of plants aet? § 982. What substances are ne- 
cessary to the fertility of a soil ? Mention them. How do plants act 
upon these ? From whence comes the alkali of the ashes of plants ? 
4 983. What is a frequent result of cultivation ? How is fertility restor- 
ed ? Explain the reason of rotating crops. Illustrate this by wheat and 
tobacco. § 984. What purposes are subsen^ed by humus 1 



NUTRITION OF PLANTS AND ANIMALS. 477 

which it is constantly evolving carbonic acid, and by the 
ammonia that it contains. It thus presents a constant 
source of these substances to the roots of plants. We 
have stated that humic acid, or humus, not only combines 
with the ammonia of the atmosphere, but is able to form 
it by the direct absorption of nitrogen, (§ 940.) Many 
chemists maintain that humic acid itself constitutes a part of 
the food of plants ; and that it combines with the elements 
of water and ammonia to generate the various products of 
the vegetable organism. This view has been ably defended, 
but we have no evidence that it is absorbed by plants, while 
it is certain it is not necessary to their growth. There are 
many plants which are capable of growing without any con- 
nection with the soil ; they may be suspended from the ceil- 
ing, and will continue to grow luxuriantly for years. In these 
plants, the process of nutrition is apparently the same, as in 
those which derive their support from the earth. They ab- 
sorb carbonic acid, ammonia and water from the atmosphere, 
and form ligneous fibre and proteine like other plants. The 
amount of mineral matter which they contain is small, and 
is doubtless derived from dust constantly floating in the at- 
mosphere, which collects upon the leaves and is dissolved 
and absorbed.' We have here vegetables subsisting entirely 
upon the ingredients of the atmosphere, and the results of 
experiment seem to show that all plants are nourished by the 
same substances, and that the only agency of humus is to 
afford carbonic acid and ammonia. 

^ 985. From what has been stated, it is easy to understand 
why ammoniacal salts are such efficient fertilizers of the soil. 
Plants watered with a weak solution of the sulphate, or 
any other salt of ammonia, grow very rapidly, and often at- 
tain tv^^ice the size and strength of tbose growing without 
this treatment. The beneficial effects of guano and urine 
are due, in part, to the ammonia which they afford. Guano 
consists of the excrements of sea-birds who resort in great 
numbers to small rocky islands on the coasts of South Amer- 
ica and Africa, The recent excretion consists of urate of 



What is the opinion of some chemists as to its use ? Have we any 
evidence of this ? How are air-plants noiirislied ? What is the concki- 
sion from experiment? § 985. What is the effect of sahs of ammonia oa 
soils ? To what is this due ? What manures owe a pait of their effi- 
ciency to ammonia ? What is guaao ? 



478 ORGANIC CHEMISTRY. 

ammonia, with various inorganic salts, but the uric acid is 
gradually decomposed and affords oxalate of ammonia. 
Wheat manured with guano is found to contain a quantity 
of azotized matter, twice as great as that raised on the same 
soil without any manure ; this is attributable principally to 
the absorption of the ammonia. 

§ 986. The food of both herbivorous and carnivorous ani- 
mals consists of proteine in its various forms, with starch, 
sugar, fat, and gelatine. Those subsisting on vegeta- 
bles, appropriate the albumen and fibrine which these bodies 
contain, for the formation of muscular tissues, that finally 
become the food of carnivorous animals. The proteine 
compounds, which alone can form blood and muscle, are ob- 
viously distinguished from the non-azotized substances that 
constitute a large portion of the food of many animals. 
Liebig conveniently designates them as the Elements of Nu- 
trition, while gelatine and all non-azotized food are called 
Elements of Respiration, as they are supposed to be in a 
great measure consumed in that process. 

^ 987. The nature of the digestive process has been al- 
ready noticed, (^ 965.) The substances taken as food are re- 
duced by the fluids of the stomach to a state of solution. 
They then pass into the small intestines, where the lacteals 
take up the portions which have been rendered soluble, and 
fitted for the purposes of nutrition. The saccharine and 
farinaceous portions of the food have never been observ- 
ed in the chyle, but the blood, shortly after saccharine 
substances have been taken into the slom.ach, contains a 
very appreciable quantity of them. It is well known that 
water and saline fluids are directly absorbed by the blood- 
vessels of the linino^ membrane of the stomach, and it is 
probable that alimentary substances in a state of complete 
solution are taken into the circulation in the same manner. 
These soon disappear from the blood, and are supposed to be 
oxydized in the lungs. 

^ 988. The non-azotized matters taken into the stomach are 

What is said of wheat manured with guano ? § 986. Of what does 
the food of animols consist? What relation have vegetables to the food 
of carnivorous animals? How are the alimentary substances distin- 
guished? What are included under the elements of nutrition? What 
are the elements of respiration ? 987. Describe the process of digestion ? 
What is said of the absorption of soluble substances ? ^ 988. What is 
said of the conversion of starch and sugrar into fat? 



L 



NUTRITION OF PLANTS AND ANIMALS. 479 

probably in part converted into fat. The most complete and 
satisfactory experiments have proved, that fat is really formed 
in the system, and is not, as was formerly supposed, derived 
from that contained in the food. Geese fed upon corn, are 
found to secrete an amount of fat much greater than is con- 
tained in the maize eaten by them, and bees form v^'ax if fed 
upon sugar. We are indeed able to form one of the fatty 
acids of butter, (butyric acid), from starch or sugar by fer- 
mentation. It is only by supposing it to be formed in the 
alimentary process, that we can account for the constant 
presence of fat in the chyle. 

The proteine compounds in the chyle require merely the 
organizing power of the vital force to give them the form of 
muscular tissue. 

^ 989. In the living body there is a constant waste of the 
tissues; the chemical forces, aided by the agency of the oxy- 
gen of the air, are producing a transformation of the muscu- 
lar and adipose substances into simpler products, which are 
excreted from the body in various ways. Baron Liebig 
has shown that a simple relation exists between the compo- 
sition of the muscular fibre and the elements of the bile and 
urine ; so that choleic acid and urea may be formed from 
it, by the addition of a little oxygen. The urea and uric 
acid contain the more azotized portions, and the bile those 
which are rich in carbon. The fatty tissues on the contrary 
appear to be completely converted into carbonic acid and 
water. The object of nutrition is to preserve the equilibri- 
um of the system by supplying the waste of the tissues, and 
so long as this balance is maintained, the organism is in a 
healthy condition. When the amount of non-azotized food is 
greater than is consumed in the process of respiration, the ex- 
cess is secreted in the form of fat, and sometimes increases to 
an enormous extent, as is seen in the fattening of domestic 
animals. If, however, the supply is stopped, the reverse 
process commences ; the secreted fat is taken into the sys- 
tem and oxydized, and as there is no way to supply its loss, 
is soon completely absorbed. 

Give some illustrations of its formation. What is said of its presence 
in the chyle? What chaniye do the proteine compounds undera;o iu as- 
similation? § 989. What changes are constantly takinof place in thes\'^- 
tem? AVhat is the result of them? Into what substances is the muscu- 
lar tissue converted ? What is the result of theoxydation of fat ? What 
is the ohject of nutrition? To what is the secretion of fat due? What 
is the result of starvation ? 



480 ORGANIC CHEMISTRY. 

§ 990. The act of respiration has for its object, to bring the 
blood into contact with the oxygen of the atmosphere. In 
the higher orders of animals, this is accomplished through 
the lungs. These organs have a cellular structure, and are 
composed of a great number of cavities capable of infla- 
tion with air. Over the surfaces of these, are spread the 
minute branches of the pulmonary artery, and the blood is 
consequently brought into close contact with the air. In the 
process oxygen gas is absorbed, and carbonic acid gas ex- 
pelled. The relative proportions which the oxygen absorb- 
ed, and the carbonic acid exhaled, bear to one another, 
are determined by the law of the mutual diffusion of 
gases already mentioned, (^ 132.) By this law, the vol- 
umes of any two gases which pass through a porous 
medium to mingle with each other, will be in the in- 
verse proportion of the square roots of their specific gravi- 
ties. The volume of oxygen that passes invvard, will ex- 
ceed that of the carbonic acid which passes outward, in 
the proportion of 1174 to 1000. As carbonic acid contains 
exactly its own volume of oxygen, it follows that 174 parts 
or nearly 15 per cent, more of oxygen are absorbed by 
the lungs than are given out in the form of carbonic acid. 
A portion of this excess of oxygen unites with the sulphur and 
phosphorus of the original components of the body, convert- 
ing them into sulphuric and phosphoric acids, and the re- 
mainder probably combines with the hydrogen of the fatty 
matter to form part of the water which is exhaled from the 
lungs. 

^991. The changes produced upon the blood by respi- 
ration have been already described, (^ 962.) This pro- 
cess is essential to life, and even in the lower orders of 
marine animals, is effected through the aid of oxygen dis- 
solved in the water, (^ 405.) Experiments have shown 
that the amount of carbon given off from the lungs by a full- 
grown man, is about 7 ounces in twenty-four hours. This 



§ 990. What is the object of respiration ? Describe the structure of 
the kmgs. What is the result of the action of the air upon the blood? 
What law regulates the absorption and evolution of the gases? What 
proportion do they bear to each other? What amount of oxygen is re- 
tained? How is it consumed? §991. What changes are produced on 
the blood in this process ? How is it effected in some of the lower animals? 
What amount of carbon is given off from the lungs of man ? What is 
the result of this oxydation ? 



NUTRITION OF PLANTS AND ANIMALS. 481 

oxydation, or slow combustion of carbon, must necessarily 
evolve heat, and is doubtless one source of the heat of the 
animal system ; but the temperature of living animals is due 
in part to the other changes which are going on in the or- 
ganism. In some cases of disease, when the respiratory 
function has been almost entirely suspended for hours, the 
temperature of the body has remained undiminished. 

^ 992. Vegetables have to a certain extent the power of 
maintaining a temperature above that of the atmosphere ; 
this is particularly observed in the leaves and young shoots, 
where vegetation is most active. In the flowering of some 
species of Arum, a thermometer placed among the spadices 
has been observed to rise to 121°, when the temperature of 
the atmosphere was only 66°. Experiments have shown 
that in this case it is due to the absorption of oxy- 
gen, but it is hardly probable that such is the general 
cause. When we consider that heat is evolved in very 
many changes which are often independent of the absorp- 
tion of oxygen, there is no difficulty in accounting for 
its production in the processes of nutrition and assimilation. 

^ 993. It is, however, true that in health, the oxyda- 
tion of carbon may be taken as a measure of the heat evolv- 
ed. The inhabitants of Greenland and other northern coun- 
tries consume in their food immense quantities of fat and 
oil, and voyagers in these regions, have found such a diet not 
only healthful, but even necessary, to enable them to endure 
the intense cold to which they were exposed. 

§ 994. In those animals which subsist entirely upon flesh, 
the amount of oxygen absorbed is not less than in the her- 
bivorous, and the oxydizing process is at the expense of the 
muscular tissue. The waste of this is consequently much 
greater than in those animals subsisting upon a mixed 
diet, the fat and starch of which supply the demands of the 
respiratory process. 

To what else is the animal heat probably due ? What cases are men- 
tioned as illustrating this? § 992. What is said of the heat of vegetables? 
To what is this ascribed? What remark is made regarding the sources 
of heat? § 993. What relation has the oxydation of carbon to heat, in 
healthy animals? What is said of the food of Greenlanders ? What of 
the experience of travelers ? How is the fat consumed ? § 994. How 
is the oxydizing process carried on in carnivorous animals? 

41 



482 ORGANIC CHEMISTRY. 

§ 995. The lifeless particles of the inorganic world are 
assimilated by plants from the atmosphere, the soil, and the 
waters. Once taken into their structure, they are trans- 
formed by the vital force into woody fibre, starch, sugar, and 
proteine, which afford the materials for the nutrition of 
animals, and supply the constant demand of the respira- 
tory functions. By the regular processes of life these are 
again set free in their original forms of carbonic acid, ammo- 
nia, and water, and are once more ready to enter the upward 
current of organic life. 

By a beautiful adjustment of these organic forces, the 
balance of the two great kingdoms of nature is maintained. 
The carbonic acid set free by the processes of combustion, 
and the respiration of animals, fails to vitiate the purity of 
the atmosphere, because the vegetable kingdom appropri- 
ates all the carbon of this gas for its own support, and restores 
an equal volume of pure oxygen to the air. 

The mind rests with equal pleasure and admiration on 
these beautiful laws, which silently, but unceasingly, work 
out an expression of the Almighty Will. 

§ 995. What is the progress of matter from the mineral to the animal 
form ? What is the result of tiiis arranvrement ? How is the purity of 
the atmosphere preserved? How may we view this beautiful system? 



L 



APPENDIX. 483 



APPENDIX. 

§ 996. Salicine. — The late researches of Piria have shown that sali- 
ciue may be viewed as a compound of grape sugar and a body which 
he has Y\dt.medisaligenine. When a solution of salicine is mixed with syn- 
aptase (§ 769) and digested for some time at 105°, F., it is decom- 
posed ; sah'genine separates in fine rhombohedral crystals, while pure grape 
sugar remains in solution. This substance is readily soluble in water, alco- 
hol, and ether ; its formula isCi4H804; when treated with dilute acids it 
is changed into saliretine, by the loss of 2 equivalents of water, and the 
same decomposition is produced by a heat of 300°. The composition of 
saliretine may be expressed by C14HGO2. The first action of acids 
upon salicine is to liberate saligenine, which, by the farther action of the 
acid forms saliretine. When brought in contact with chromic acid, oxyd 
of silver, or other oxydizing substances, saligenine is converted into hyd- 
ret of salicyle and water ; the same change is produced when it is mixed 
with platinum black, (§ 366.) This reaction is produced by the addition 
of 2 equivalents of oxygen; Ci4H8 04-j-20=2HO+Ci 4H6O4. As 
salicine contains the elements of 1 equivalent of saligenine and 1 of 
grape sugar, its true formula isC26Hi80i4. 

A solution of salicine in cold dilute nitric acid, gradually deposits crys- 
tals of a new substance, named helicine. This is formed from salicine, 
by the loss of 2 equivalents of hydrogen ; it contains the elements of 
grape sugar and hydruret of salicyle, and is resolved into these bodies by 
synaptase, or boiling dilute acids. With a hot solution of potash, it forms 
salicyd of potassium. 

§ 997. Gun Cotton. — This substance is a form of the Xyloidine discov- 
ered by Braconnot, which is produced by the action of concentrated nitric 
acid, specific gravity, 15, upon starch or any form of woody fibre. The 
complete conversion of the cotton into xyloidine is difficult, but the action of 
the nitric acid is facilitated by a mixture of strong sulphuric acid. 100 
grains of clean cotton may be immersed for five minutes in a mixture of 
li ounces by measure of nitric acid specific gravity 1*45, with an equal 
bulk of strong oil of vitriol. After its removal from the acid, the cotton 
is to be thoroughly washed with large quantities of water and dried at a 
temperature not exceeding 212° Y. As thus prepared, it retains the struc- 
ture and appearance of ordinary cotton ; it is highly inflammable, taking 
fire at the low temperature of 360° F., and readily explodes by the blow of 
a hammer. Unsized paper dipped in the acid, is in part changed into xy- 
loidine, and is made more translucent, very tough, and quite impervious to 
water, resembling vellum. 

The analysis of xyloidine gives for its composition C6H4NO9 : or, 
doubling the formula, C12H8N2O1 g. It may be viewed as starch or 
cellulose, in which 2 equivalents of nitrous acid replace 2 of hydrogen. 
Cellulose is Ci2HloOio> and xyloidine will be C12H82NO4O10. 
The quantity of oxygen which it contains is sufficient to convert the hy- 
drogen into steam and the carbon into carbonic acid and carbonic oxyd, 
so that its combustion produces an immense volume of gas and leaves no 
solid residuum. Its explosive power is much greater than that of gun- 
powder, and as it does not vitiate the air, it will be valuable in mining ope- 
rations, but great care will be required in its use, from the comparatively 
low temperature at which it explodes. 



484 



TABLE OF ANALYSES OF 



(referred to 



Nos. 1 to 6 inclusive, show the ingredients in 1 American standard 

and Nos. 9 and 10 



1 




(1) 


(2) 


(3) 


(4) 


Ingredients. 


Schuylkill 
River. 


Croton 
River. 


Charles 
River. 


Spot 
Pond. 


Chlorid of Potassium, 


.. 




.. 


.. 


2 


Chlorid of Sodium, 


•1470 


•167 


-1547 


•3969 


3 


Chlorid of Ammonium, 


•• 




•• 


•. 


4 


Chlorid of Calcium, 


.. 


•372 


•0420 


.. 


5 


Chlorid of Magnesium, 


•0094 


•• 




•• 


6 


Chlorid of Aluminium 


•• 


•166 


•• 


•• 


7 


Bromid of Sodium, 




•. 


.. 


.. 


8 


Bromid of Magnesium, 


•• 


•• 


" 


•• 


9 


lodid of Sodium, 


•• 


•• 


•• 


" 


10 


Sulphate of Potash, 


•• 


•• 




•• 


11 


Sulphate of Soda, 


•• 


•153 


•3816 


•2276 


12 


Sulphate of Lime, 


•• 


•235 


•2624 


.. 


13 


Sulphate of Magnesia, 


•0570 


." 


•• 


•• 


14 


Sulphate of Alumina, 


•• 


•• 


•• 


•• 


15 


Nitrate of Magnesia, 


•• 


•• 


•• 




16 


Phosphate of Lime, 


•• 


•• 




and iron. 


17 


Phosphate of Alumina, 


•• 


•832 


0973 


•1081 


18 


Alumina, 


" 


•• 


•• 


- 


19 


Silicic Acid, 


•0800 


•077 


traces 


traces 


20 


Carbonate of Soda, 


•• 


•• 


•• 


•• 


21 


Carbonate of Baryta, 


•• 






•• 


22 


Carbonate of Strontia, 


•• 




•• 




23 


Carbonate of Lime, 


1-8720 


2131 


•1610 


•3722 


24 


Carbonate of Magnesia, 


•3510 


•662 


•0399 


•1420 


25 


Carbon, of Manganese, 


•• 


traces 


•• 


*• 


26 


Carbonate of Iron, 


•• 




•• 


„ 


27 


Fluorid of Calcium, 
Salts of Soda with the ) 


*• 


" 


„ 


„ 


28 


Nitric and Organic > 
Acids, ; 

Total, 


1'6436 


1-865 


•5291 


" 


4-2600 


6-660 


1-6680 


1-2468 




Carbonic Acid Gas ) 
in cubic inches, ^ 


3-879 


17-418 


•0464 


38-79 




Analyzed by 


Author. 


Author. 


Author. 


Author. 



Note. — No. 1 is the supply for the city of Philadelphia, No. 2 for New 
York, and No. 5 for Boston ; Nos. 4 and 6 are small lakes in the vicinity 
of Boston, and No. 3 is a river in Massachusetts, emptying near Boston. 



NATURAL WATERS, 



485 



IN ^ 405.) 

gallon, (or 58*372 grains.) Nos. 7, 8, and 9 are in one pound Troy, 
in 1000 parts. 





(5) 


(6) 


(7) 


(8) 


(9) 


(10) 


Long 


Mystic 


Saratoga 


Seltzer 


Sea Water 


Water of 


1 


Pond. 


Pond. 


C. Spring, 


Spring. 


Brit. Chan. 


Dead Sea, 


•0380 


•1590 


1-6256 


•2685 


•7660 


traces 


2 


•0323 


27-911 


19-6653 


12-9690 


27-9590 


78-650 


3 




•• 


•0326 




traces 


•• 


4 


•0308 


•1544 


•• 


" 


•• 


28-220 


5 
6 

7 


•0764 




•• 


" 


3-666 


50-950 






•1613 


.. 


.. 


.. 


8 


•• 


•. 


•• 


•• 


•0290 


7-950 


9 


•• 




•0046 


- 


traces 


•• 


10 


•• 


•. 


•1379 


•2978 


" 


•• 


11 


•• 


•• 


•• 


•• 


•• 


•• 


12 


•• 


1-2190 


•• 


•• 


1-4060 


traces 


13 


•1020 


1-9768 




•• 


2-2960 


" 


14 




•4478 


•• 


•• 




•• 


15 


•• 


•• 


•1004 


•• 


•• 


•• 


16 


.. 


.. 




•0007 


.. 


•• 


17 


.. 


•2810 


•• 


•0020 




" 


18 


•0800 . 


.. 


•0069 






• 


19 


•0300 


•5559 


•1112 


•2265 


•• 


•• 


20 


•• 


.. 


•8261 


4^6162 


.. 


•• 


21 


.. 






•0014 


.. 


•• 


22 




.. 


•0672 


•0144 




•• 


23 


•2380 


•9894 


5-8531 


1-4004 


•0330 


•• 


24 


•0630 ' 


•1698 


4-1155 


1-5000 


•• 




25 


•• 


" 


•0202 




.. 


•• 


26 


•• 


•• 


•0173 


" 


.. 




27 


•• 


•• 


•• 


•0013 


•• 


•• 


28 


•5295 


•• 


•• 


" 


•• 




1-2220 


327671 


34-7452 


21-2982 


35-255 


165-770 








in 100 


c in 








10-719 


10313 


114- 


126- 








Author. 


Author. 


Schweitzer. 


Struve. 


Schweitzer. 


Author. 



No. 7 is the well known "Congress Spring." No. 8 is a celebrated 
German Spa. 

No. 10 was collected by J. D. Sherwood, Esq., April, 1843, near the 
mouth of the Jordan. 

41* 



INDEX. 



*;^* The references are to the numbers of the sections. 



Acetates, 811. 

Acetone, 820. 

Acetyle, hydrated oxyd of, 804. 

Acid, acetic, (acetylic,) 807 ; acon- 
itic, 868 ; aldehydic, (acetylous,) 
806 ; anilic, 913 ; antimonic, 6.31 ; 
antimonious, 631; arsenic, 636; 
arsenious, 635 ; benzoic, 762 ; bo 
racic, 369 ; bromic, 273 ; butyric, 
889 ; carbazotic, 913 ; carbolic 
945 ; carbonic, 338 ; cerebric, 
972 ; chloracetic, 684 ; chloric, 
270 ; chlorocarbonic, 709 ; chlo 
rochromic, 602 ; chlorous, 268 ; 
choleic ; 967 ; chromic, 600 ; 
cinnamic, 773 ; citraconic, 868 ; 
citric, '867 ; columbic, 619 ; co- 
menic, 878 ; cyanic, 720 ; cyanox- 
ahc, 755 ; cyanuric, 726 ; enan- 
thic, 890 ; ethalic, 863 ; ferric, 
594 ; ferridcyanic, 742 ; ferrocy- 
anic, 739 ; fluoboric, 372 ; fluosi- 
licic, 363; formic, 849; fulminic, 
724 ; fnmaric, 874 ; gallic, 877 ; 
hippuric, 771 ; humic, 939 ; hy- 
driodic, 422; hydrobromic, 421; 
hydrochloric, 415; hydrocyanic, 
730 ; hydrofluoric, 424 ; hydro- 
mellonic, 753 ; hydrosalicylic 
775 ; hydroselenic, 435 ; hydro- 
sulphuric,428 ; hypochlorous,266 ; 
hyponitrous, 308 ; hypophospho- 
rous, 320 ; hyposulphuric, 284 ; 
iodic, 277 ; isatinic, 910 ; kako- 
dylic, 824; kinic, 879; lactic 
839 ; malic, 874 ; manganic, 583 ; 
margaric, 884 ; meconic, 878 ; 
metaphosphoric, 323; molybdic, 
619 ; mucic, 832; muriatic, 
415 ; nitric, 310 ; nitroben- 
zoic, 768; nitromuriatic, 419; ni- 



trophenisic, 945 ; nitropicric, 913 
nitrosalicyiic, 778 ; nitrous, 309 
oleic, 885 ; osmic, 645 ; oxaliC; 
710; pectic, 935; perchloric, 
265 ; periodic, 277 ; perman 
ganic, 583 ; phosphethylic, 801 
phosphoric, 322 ; picric, 913 
prussic, 730 ; pyroligneous, 809 
pyrophosphoric, 323 ; quercitan- 
nic, 876 ; racemic, 873 ; saccha- 
ric, 830 ; salicylic, 776 ; sebacic, 
885 ; selenic, 297 ; selenious, 297 ; 
silicic, 358 ; stannic, 622 ; stearic, 
883 ; suberic, 887 ; succinic, 887 ; 
sulphamyhc, 857 ; sulphethylic, 
(sulphovinic,) 799 ; sulphindigo- 
tic, 909 ; sulphocetylic, 861 ; sul- 
phocyanic, 749 ; sulphomethylic, 
848; sulphurous, 285; sulphuric, 
288 ; tannic, 875 ; tartaric, 869 ; 
telluric, 644 ; tellurous, 644 ; ti- 
tanic, 619 ; tungstic, 619 ; ulmic, 
939 ; uric, 755 ; valeric, (valeri- 
anic,) 858. 

Acids, 194 ; organic, 866 ; theory 
of, 485. 

Aconitine, 925. 

Acroleine, 882. 

Affinity, chemical, 205. 

Agriculture, chemistry of, 982. 

Air-pump, 28. 

Air, analysis of, BOl; 

Albumen, animal, 954 ; vegetable, 
951. 

Alcohol, 788; amylic, 855; methy- 
lic, 844. 

Aldehyde, 804. 

Aigaroth, powder of, 632. 

Alizarine, 901. 

Alkalies, 490. 

Alkalimetry, 509. 



INDEX. 



487 



Alkaloids, 915. 

Alkargene, 824 ; Alkarsine, 823, 

AUantoine, 756. 

Allotropism, 263 ; in organic com- 
pounds, 687. 

Alloxan, 757 ; Alloxantine, 758. 

Alloys, 478. 

Allyle compounds, 896. 

Almonds, essential oil of bitter, 761. 

Alumina, 572 ; acetate of, 811 ; si 
icates of, 575 ; sulphate of, 573. 

Aluminum, 571 ; chlorid of, 572. 

Alum, 573. 

Amalgams, 651. 

Amber, 897. 

Amidogen, see Ammidogen. 

Amiline, 859. 

Ammidogen, 445, 705 ; chlorid of, 
&c., 708. 

Ammidids or amides, 705. 

Ammonia, 437; acetate of, 811; 
cyanate of, 721 ; hydrosulphuret 
of, 543 ; oxalate of, 713 ; present 
in the atmosphere, 438 ; salts of 
ammonia, 542; water of, 441 ; 
use of as a fertilizer, 895. 

Ammonium, 444, 541 ; chlorid of, 
sulphuret of, 543 ; theory of, 541. 

Amygdaline, 769. 

Amyle, compounds of, 854. 

Analysis of organic bodies, 693. 

Anatase, 619. 

Anilene, 910. 

Animals, nutrition of, 976 ; food of, 
9&6. 

Anthracite, 941. 

Antimony, 629 ; compounds with 
oxygen, 630 ; chlorids of, 632 ; 
sulphuretsof, 633 ; tartrate of, and 
potash, 871. 

Aqua regia, 419 ; ammonise, 441 ; 
fortis, 310. 

Arabine, 934. 

Arbor, Dianae, 663 ; Saturni, 612. 

Arsenic, 634; as a poison, detec- 
tion of, 639 ; chlorids of, 637 ; 
compounds of, with oxygen, 635 ; 
Fresenius' and Von Babo's test 
for, 642 ; Marsh's do., 643 ; re- 
duction of, 641 ; sulphurets of, 637. 

Arseniureted hydrogen, 638. 

Assafetida, oil of, 896. 

Athamantine, 891. 



Atmosphere, chemical history of, 
300 ; mechanical properties of, 24. 

Atomic theory, 212 ; weights, table 
of, 187. 

Atoms,8 ; specific heat of, 214; po- 
larity of, 217. 

Attraction of gravitation, 8. 

Atropine, 924. 

Aurum Musivum, 624. 

Azote, see Nitrogen. 

Balance, 37 ; of organic forces, 99.5. 

Barium, 549 ; chlorid of, 551. 

Barometer, 33. 

Baryta, 550 ; carbonate of, 553 ; 
nitrate of, 552 ; sulphate of, 552. 

Batteries, galvanic, 163 ; sustaining, 
243. 

Benzamide, 764 ; Benzoine, 766. 

Benzile, 767 ; Benzole, 765. 

Benzoyle, 760 ; ammidid of, 764 ; 
chlorid of, 763 . hydruret of, 761. 

Bile, 967. 

Bismuth, 625 ; oxyd of, 626 ; ni- 
trate of, 627. 

Bleaching powders, 564. 

Blood, 960. 

Blowpipe, compound, 399 ; mouth, 
469. 

Blue pill, 651. 

Boiling, 119. 

Bones, 974. 

Boracic ether, 797. 

Boron, preparation and properties, 
366 ; compound with oxygen, 
368 ; chlorid of, 371 ; fluorid of, 
372. 

Borax, 537. 

Brain and nervous matter, 972. 

Bread making, 953. 

Bromine, history and preparation of, 
271. 

Brucine, 923. 

Brookite, 619. 

Butter and butyrine, 889. 

Cadmium, 608. 

Caffeine, 926. 

Calcium, properties of, 556 ; chlorid 
of, 559 ; fluorid of, 561 ; oxyd of, 
557. 

Calculi, urinary, 971. 

Calomel, 653. 

Camphene, 893. 

Camphor, 895 ; artificial, 893. 



488 



INDEX. 



Caoutchouc, 898. 

Capacity for heat, 106. 

Capillary attraction, 21. 

Capsicine, 925. 

Carthaniine, 901. 

Carbureted hydrogen, heavy, 455. 
" " hght, 452. 

Carmine, 904. 

Carbon, properties and history, 329 ; 
bisulphuret of, 351 ; clilorids of, 
819 ; compound with nitrogen, 
353 ; compounds with oxygen, 
337 ; oxyd of, 346, 709. 

Caseine,955; vegetable, 951. 

Cassius, purple of, 623, 649. 

Cellular tissue, formation of, 979. 

Cellulose, 936. 

Cerium, 579. 

Cetene, 863 ; cetyle, 860. 

Chamelion mineral, 583. 

Charcoal, 334 ; absorbs gases and 
odors, 335. 

Chemical affinity, 205 ; attraction, 
12; nomenclature, 192; philoso- 
phy, 181. 

Cinchonine, 921. 

Chloranile, 914. 

Chloric ether, 852. 

Chlorine, preparation and properties, 
259; allotropism of, 263; com- 
pounds with oxygen, 265. 

Chlorisatine 911. 

Chloroform, 852. 

Chlorophyle, 902. 

Cholesterine, 967. 

Chondrine, 959. 

Chromium described, 597; chlorids 
of, 599 ; compounds with oxygen, 
598. 

Cinnamyle, 772. 

Chyle, 964. 

Classification of elements, 249. 

Cleavage of crystals, 226. 

Coal, 333, 941 ; gas from, 458 ; pro- 
ducts of its distillation, 944. 

Cobalt described, 605 ; chlorid of, 605. 

Cobaltocyanogen, 744. 

Codeine, 923. 

Cohesion, 10. 

Colophony, 897. 

Coloring matters described, 899 ; 
red, 901 ; from lichens, 903 ; 
yellow, 900. 

Columbium and columbite, 619. 



Combination, laws of, 183 ; by vol- 
ume, 189. 

Combustion, nature of, 460 ; heat 
of, 463 ; and structure of flame,460. 

Compound radicals described, 677 ; 
defined, 679. 

Congelation, 109. 

Conine, 920. 

Contact, theory of, 691. 

Copal, 897. 

Copper described, 615 ; alloys of, 
621 ; nitrate of, 618; oxyds of, 
616 ; sulphate of, 617. 

Corrosive sublimate, 653. 

Cryophorous, 123. 

Crystallization, nature of, 215. - 

Crystals, measurement of, ^7 ; 
primary forms of, -^18. 

Cupellation, 660. 

Cyanids, 733 ; double, 736. 

Cyanogen, 353, 715 ; compounds 
with bromine, chlorine, &c., 728; 
hydrogen, 730 ; metals, 733 ; oxy- 
gen, 718 

Daniell's battery, 244. 

Davy's safety lamp, 471. 

Decomposition of water, 234, 387. 

Den:>ity, 37. 

Dew point, 133. 

Dextrine, 932. 

Diabetic sugar, 828. 

Diamond, history and forms of, 329. 

Diachylon plaster, 886. 

Diastase, 933. 

Digestive process, nature of, 966. 

Dimorphism, 232. 

Doberiner, observations on platinum, 
396. 

Drummond light, 402. 

Dutch liquid, 455, 817. 

Electricity, 145 ; theories of, 149. 

Electro-chemical decomposition, 
233 ; conditions of, 236 ; magnet- 
ism, 165 ; magnetic telegraph, 
178 ; metallurgy, 247. 

Electrophorous, 154. 

Electroscopes, 151. 

Elements, laws of combination in, 
181 ; non-metallic, classified, 249 ; 
metallic, classified, 489. 

Emetine, 925. 

Emulsine, 769. 

Equivalents, table of, 187. 

Eremacausis, 939. 



INDEX. 



489 



Ethal, 860. 

Ether, acetic, 816; benzoic, 798; 
boracic, 797 ; chloric, 852 ; hy 
drobromic, 791 ; hyponitrous, 796 ; 
methylic, 843 ; mucic, 832 ; ni 
trie, 795; oxalicr798; sulphuric 
784. 

Etherine and etherol, 803. 

Ethyle, 783; compared with me- 
thyle, amyle, and cetyle, 864 ; 
acetate of, 816; acid compounds 
of, 799 ; chlorid, bromid, and sul- 
phuret, 790 ; hydrated oxyd of, 
788 ; oxyd of, 784 ; products of 
its decomposition, 802. 

Euchlorine, 266. 

Eudiometry,301 ; by hydrogen, 394 

Eupione, 943. 

Evaporation, ]29. 

Expansion by heat, 71 ; of solids 
and liquids, 28, 73, 74. 

Faraday's researches, 235. 

Fatty substances described, 880. 

Fattening of animals, 988. 

Feldspar, 575. 

Fermentation, viscous, 837 ; vinous, 
834. 

Ferridcyanogen, 742. 

Ferrocyanogen', 738. 

Fertilizers, 983,985. 

Fibre, woody, 936. 

Fibrine, animal and vegetable, 954, 
951. 

Flame, structure of, 465. 

Fluorine, history and properties, 
279. 

Fluorspar, 561. 

Fluids, properties of, 19. 

Formiates, 851. 

Formyle, 849 ; compounds of, 852. 

Freezing mixtures. 111. 

Fresenius' and Von Babo's test for 
arsenic, 642. 

Fuseloel, 855. 

Fusible metal, 628. 

Galena, 611. 

Galvanism, 157; quantity and in- 
tensity in, 162. 

Galvanic batteries, 163, 243. 

Galvanoscopes, 166. 

Gases, laws of, 24 ; liquefaction of, 
136 ; management of, 256. 

Gasholders, 257. 



Gastric juice, 965. 

Gelatine, 959. 

German silver, 604. 

Glass, manufacture of, 539. 

Ghicinum, 579. 

Glucose, 828. 

Gluten, 951. 

Glycerine, 882. 

Gold, 646 ; oxyds and chlorid of, 
648 ; cyanid of, 735. 

Goniometer, common, 227; Wol- 
laston's, 228. 

Grape sugar, 828; fermentation of, 
835. 

Graphite, 332. 

Greenockite, 608. 

Grove's battery, 245. 

Gum, 934 ; elastic, 898. 

Gun cotton, 997. 

Gunpowder, composition of, 517. 

Gypsum, 560. 

Heat, communication of, 89 ; ex- 
pansion by, 71, 82 : radiant, 97 ; 
sources of, 70 ; specific, 106 ; 
transmission of, 103 ; of the ani- 
mal body, 991, 993. 

Heavy spar, 552. 

Helicine, 996. 

Hematine, 961. 

Hematite, red and brown, 580. 

Hematoxyline, 901. 

Hemming's safety tube, 401. 

Henry's coils, 174. 

Humus, 939. 

Hydrogen, preparation and proper- 
ties, 374 ; nature of 382 ; acids 
of, 412 ; action with chlorine, 
414; arseniureted, 638 ; com- 
pound with boron, 459 ; bromine, 
421 ; carbon, 450; chlorid, 415 ; 
fluorine, 424 ; iodine, 422 ; nitro- 
gen, 436 ; oxygen, 383 ; phos- 
phorus, 446 ; selenium, 435 ; sul- 
phur, 428: peroxyd of, 409. 

Hydrometer, 47. 

Hydrosulphiiret of ammonium, 543. 

Hydruret of benzoyle, 761 ; cinna- 
myle, 772; salicyle, 775. 

Hygrometers, J 34. 

Imponderable agents, 15. 

Indigo, 906. 

Ink, bla2k, 876 ; blue, 741. 

Inuline, 933. 



490 



INDEX. 



Iodine, 274 ; compounds with oxy 
gen, &c., 277. 

Iridium, 665. 

Iron, 586 ; chlorid of, 594 ; cyanid 
of, 734 ; ferrocyanid, 740 ; oxyds 
of, 592 ; reduction of its ores, 590 
salts of, 596 ; specular, 589 ; sul- 
phurets of, 595 ; two states of, 
588. 

Isatine, 910 ; Isatyde, 912. 

Isomerism, 688. 

Isomorphism, 230. 

Kakodyle, 821 ; chlorid of, 825 ; 
protoxyd of, 823. 

Kermes mineral, 633. 

Kinone, 879. 

Kyanite, 575. 

Kyanizing process, 653. 

Kyanol, 947. 

Lactates, 841 ; Lactide, 840. 

Lactine, 831. 

Lamp, Davy's safety, 471 ; Jack- 
son's, 468. 

Lantanum, 579. 

Laughing gas, 303. 

Lard oil, 886. 

Lead, 609 ; acetate of, 812 ; car- 
bonate of, 613, 813 ; chromateof, 
602 ; oxyd of, 610 ; plaster or diach- 
ylon, 886 ; precipitated by zinc, 
612; sulphuret, 611. 

Leather, 959. 

Lecanorine, 904. 

Legumine, 951. 

Leiocome, 932. 

Leyden jar, 153. 

Leukol, 920, 947. 

Light, properties of, 52 ; latent, 66 ; 
sources and nature, 51. 

Lignine, 936. 

liime, 557 ; carbonate of, 563 ; 
chlorid of, 564 ; lactate of, 841 ; 
oxalate of, 714 ; phosphates of, 
562 ; sulphate of, 560. 

Liquefaction, 108 ; and solidification 
of gases, 136. 

Litmus, 903. 

Lunar caustic, 663. 

Luteoline, 900. 

Lymph, 964. 



Magnesia, 566 ; carbonate of, 569 ; 
sulphate of, 568. 

Magnesium, 565 ; chlorid of, 567 ; 
oxyd of, 566. [city, 179. 

Magnetism, 139 ; Magneto-electri- 

Malachite, green and blue, 615. 

Malt, 933. 

Malates, 874. 

Manganese, 580 ; acetate of, 811 ; 
chlorids of, 584; oxyds of, 581, 
582 ; salts of, 585. 

Marble, 563. 

Margarine, 884. 

Mariotle's law, 30. 

Marsh gas, 452. 

Marsh's test for arsenic, 643. 

Matter, general properties of, 6. 

Mellone, 752. 

Melloni's researches, 104. 

Mercaptan, 793. 

Mercury, 650 ; amniidid of, 653 ; 
chlorids of, 653 ; chlorammldid, 
707 ; cyanid of, 734 ; fulminate 
of, 725 ; iodids of, 654 ; nitrates 
of, 656 ; oxyds of, 652 ; sulphate 
of, 657 ; sulphurets, 655 ; 

Mesityle, 820. 

Metallurgy electro, 247. 

Metals, general properties of, 473. 
chemical relations of, 479 ; clas- 
sification of, 489. 

Methyle, 842; chlorid of,845 ; oxa- 
late of, 847; oxyd of, 844; 
sulphate of ,846. 

Microcosmic salt, 534. 

Milk, 973 ; sugar of, 831. 

Minderus, spirit of, 811. 

Molecules, polarity of, 217. 

Molybdenum, 619. 

Mordants, 574, 624. 

Morphine, 922. 

Mortar, 558. 

Murexide, 759. 

Mustard, oil of, 896. 

Myrosine, 896. 

Naphtha, 949 ; naphthaline, 948. 

Narcotine, 923. 

Nervous matter, 972. 

Newton's fusible metal, 628. 

Nickel and its oxyds, 603 ; sul- 
phate, 604. 



INDEX. 



491 



Nicotine, 920. 

Nitrobenzole, 765. 

Nitrogen, 829 ; compounds with 
oxygen, 302; chlorid of, 708. 

Nomenclature and symbols, 192 

Nutritive substances, ^50. 

Nutrition of plants and animals, 976 ; 
elements of, 986. 

Oil of bitter almonds, 761 ; lard, 
886; palm, 888; potato, 855; 
of the Dutch chemists, 817 ; spi- 
rea, 775; turpentine, 893. 

Oils, volatile or essential, 892 ; of 
wine, 803 ; wintergreen, 844. 

Olefiant gas, 456, 802 ; with chlo- 
rine, 457. 

Oleine, 885. 

Orceine, 904. 

Oreoseline, 891. 

Organic bases or alkaloids, 915. 

Organic bodies, general properties of, 
670 ; analysis of, 693 ; decompo- 
sition of, 690. 

Organic nature, balance of, 995. 

Organic radicals, 677. 

Osmium, 645. 

Oxygen, 251. 

Oxalyle, 709 ; compounds with ox- 
ygen, 710. 

Ozone, 411. 

Palladium, 664 ; cyanid of, 734. 

Pancreatic fluid, 966. 

Paracyanogen, 717. 

Paraffine, 949. 

Peat, 941. 

Pectine, 935. 

Pepsine, 965. 

Petalite, 575. 

Petroleum, 949 

Phenyle, 946 ; hydrate of, 777, 945. 

Phloridzine, 781. 

Phosgene gas, 348. 

Phosphorus, 314; chlorids, bromids, 
&c., 324 ; compounds with oxy- 
gen, 318; nitrogen, 328. 

Phosphureted hydrogen, 446. 

Pitchblende, 614. 

Plants, their nutrition, 978. 

Platinocyanogen, 745. 

Platinum, 667 ; chlorids and oxyds. 
669 ; power to cause the union of 
gases, 396; spunge and black, 
668. 

Polarization of light, 63. 



Potash, 495 ; acetate of, 811 ; car- 
bonates of, 507, 511 ; chromate 
of, 601 ; cyanate, 720 ; nitrate, 
515 ; salts of, 506 ; sulphates of, 
512; tartrate of, 870; tests for, 
498 ; yellow prussiate, 640. 

Potassium, 490, 492; chlorid, bro- 
mid, &c., 499, 502 ; cyanid, 
733 ; compound with nitrogen, 
505 ; ferridcyanid of, 743 : ferro- 
cyanid, 740 ; mellonid, 954 ; ox- 
yds of, 494 ; sulphocyanid, 750. 

Potato oil, 855. 

Pottery, art of, 576. 

Prussian blue, 741. 

Prussiate of potash, 740. 

Prism, its action on light, 58. 

Proteine, 956 ; relation to fibrine, 956. 

Pyroxylic spirit, 844. 

Quercitrine, 900. 

Quicksilver, 650. 

Quinine, 921 : quinoleine, 920. 

Radicals, organic, 677 ; salt, 486. 

Ratsbane, 635 ; realgar, 637. 

Red lead, 611 ; precipitate, 652. 

Reflection and refraction of light, 
54, 55. 

Rennet, 955. 

Repulsion, 11. 

Resins, 897 ; resin gas, 458. 

Respiration, 990 ; elements of 986. 

Rhodium and its compounds, 666. 

Rochelle salt, 871. 

Rutile, 619. 

Safety Lamp, 471. 

Sal-ammoniac, 542. 

Salicine, 779. 

Salicyle and its derivatives, 774. 

Saligenine, 996 ; saliretine, 779. 

Saliva, 966. 

Salts, theory of, 485. 

Sanguinarine, 925. 

Selenium, 295 ; compounds of with 
oxygen, 296. 

Seleniureted hydrogen, 435. 

Serum, 960. 

Silica, 358. 

Silicon, 355 ; chlorid of, 362 ; fluo- 
rid of, 363. 

Silver, 659 ; oxyd of, 661 ; chlorid of, 
662 ; nitrate of, 663 ; acetate of, 
815 ; cyanid of, 734 ; fulminate 
of, 724. 

Smee's Battery, 246. 



r 



492 INDEX. 

Soaps, 886. (Titanium, 619. 

Soda, 524; biborate, of, 537; car-| Tungsten, 619. 

bonates of, 527 ; nitrate of, 532 ;!Turpeth mineral, 657. 



fWH 



phosphates of, 533 ; silicates of, 
538 ; sulphate of, 530 ; acetate 
of, 811. 
Sodium, 523 ; chlorid of, 525. 
Soils, relation of to plants, 982. 
Solids, properties of, 17. 

Spermaceti, 863. 

Specific heat of bodies, 214. 

Specific gravity, 38. 

Spheroidal state of bodies, 135. 

Spirea ulmaria, oil of, 774. 

Spirit, pyroxylic, 844. 

Spodumene, 575. 

Starch, 930. 

Steam, 125 ; engine, 128. 

Stearine, 883. 

Stearoptens, 894. 

Steel, 591. 

Strontium, 554 ; chlorid of, 555. 

Strontia, 554: salts of, 555. 

Strychnine, 923. 

Sugars, 826. 

Substitution, theory of, 684. 

Sulphocyanid of potassium, 756. 

Sulphocyanogen, 748. 

Sulphur, 281 ; compounds with ox- 
ygen, 284; chlorid of, 294. 

Sulphureted hydrogen, 428. 

Symbols, chemical, 202. 

Synaptase, 769. 

Table of chemical equivalents, 187. 

Tannin, 875. 

Tartar emetic and tartrates, 871. 

Tellurium, 644. 

Telegraph, electro-magnetic, 178. 

Temperature of flame, 466 ; of in- 
candescence, 464. 

Theine, 926 ; Theobromine, 928. 

Theories of electro-chemical de- 
composition, 242: of types, 684 ; 
of substitution, 685. 

Thermo-electricity, 180. 

Thermometers, 75. 

Thorium, 579. 

Tin, 620 ; alloys of, 621 ; oxyds of, 
620 ; chlorids of, 623 ; sulphurets 
of, 624. I 

Tissues, waste of the animal, 989. 



Turpentine, oil of, 893. 

Types, theory of, 684. 

Typical characters of a group, 865. 

Ulmine, 939. 

Upas, poison of the, 923. 

Uranite, 614 ; Uranium, 614. 

Urea, 722 ; Urine, 970. 

Urinary calcuh, 971. 

Valeryle, 858. 

Valerianate of zinc, 858. 

Vanadium, 619. 

Vaporization, 115. 

Veratrine, 925. 

Verdigris, 815. 

Vermilion, 655. 

Vegetables, nutrition of, 978 ; tem- 
perature of, 992. 
Vinegar, 807 ; quick process for, 

808. 
Vinous fermentation, 834. 
Vitriol, blue, 617 ; green, 596; oil 

of, 288 ; white, 607. 
Volatile oils, 892. 
Volume, combination by, 189. 
Voltaic pile, 159. 
Voltameter, 241. 

Water, 403 ; as a chemical agent, 
408 : decomposition of Voltaic, 
234 ; formation of, 393. 
Waters, analyses of, page 484. 
Wax, 890. 

White lead, 613, 813. 
White precipitate, 658. 
Wolfram, 619. 

Wood, destructive distillation of, 942. 
Woody fibre, 936 ; transformation 

of, 939. 
Wood naphtha, 844. 
Wood spirit, 844. 
Xyloidine, 997. 
Yeast, 952. 
Yttrium, 579. 
ZafFre, 605. 

Zinc, and oxyd of, 606; chlorid of, 
607 ; sulphuret of, 607 ; lactate 
of, 841. 
Zirconium, 579. 






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